The Theories of Darwin and Their Relation to Philosophy, Religion, and Morality
by Rudolf Schmid
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Transcriber's note: A few typographical errors have been corrected: they are listed at the end of the text.


HALL, STUTTGART, April 5, 1880.

We hereby authorize the Rev. Dr. G. A. Zimmermann to translate into English the book entitled

Die Darwin'schen Theorien und ihre Stellung zur Philosophie, Religion und Moral von Rudolf Schmid.

We declare that we know of no other translation of the said book and that Dr. Zimmermann's translation will be the only one authorized by us for the United States as well as for the British Empire and its Dominions.


(The Publisher) PAUL MOSER.

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By RUDOLF SCHMID, President of the Theological Seminary at Schoenthal, Wuertemberg.




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The movement which received its impulse as well as its name from Darwin, seems to have recently passed its distinctest phase; but the more prominent points of opposition, religious, ethical, and scientific, which have been revealed through it, remain as sharply contrasted as before. The author of this book desires, in the first place, to be of service to such readers as feel the need of setting themselves right upon these questions, which touch the highest interests of mankind, but who lack time and opportunity to investigate independently a realm in which so many and so heterogeneous sciences come into mutual contact. The illogical and confused manner in which some noisy leaders confound these sciences and their problems and consequences, renders it still more difficult to arrive at a satisfactory result; and thus perhaps many readers will look with interest upon an investigation designed to simplify the different problems and the different attempts at their solution, and to treat them not only in their relations to each other, but also separately. But with this primary object, the author combines another: to render a service to some among the many who perceive the harmony between their scientific conviction and their religious need threatened or shaken by the results of science, and who are unwilling to lose this harmony, or, having lost it, desire to regain it. Those voices are indeed becoming louder, and more generally and willingly heard, which proclaim an irreconcilability between faith and {2} knowledge, between the religious and the scientific views of the world; which declare that peace between the two can only be had at the price either of permitting the religious impulses of the heart to be stifled in favor of science, of satisfying the religious need of the mind with a nourishment which in the light of science proves to be an illusion, or, as sceptics in theory and eclectics in practice, of renouncing with resignation a logical connection and foundation to their former view of the world. The most striking proof of the extent to which these voices are heard, is the fact that it has been possible for a one-sided pessimism to become the fashionable system of philosophy in a Christian nation. The most effective means for opposing such discordant voices, and for making amends for the disagreements which they have occasioned, undoubtedly consists in the actual proof of the contrary of their theories, in the clear presentation of a standpoint from which not only the most unrestricted freedom of investigation and the most unreserved acknowledgment of its results shall be in perfect harmony with the undiminished care of our entire religious possession, but in which this peace is preserved and forever established by the very fact that one function of the mind directly requires the other, one possession directly guarantees the other. This is the standpoint of the author, and from it he has endeavored to treat all the questions which are to be taken into consideration. Should he, by his exposition of this standpoint, succeed in helping even a few readers in reaching the conviction of the actual harmony between the scientific, religious, and ethical acquisitions of mankind, or in confirming them anew in such conviction, he would find himself amply rewarded for this first extended venture before the public.

R. S.



Six years have elapsed since I wrote the book which is now going forth in English dress. The great leader of the theories in question has passed away; the waves of thought he set in motion are assuming smoother shape; and I can only add to what I have already written, that not only have I had no occasion to retract any of the statements or views laid down in the book, but I perceive the religious as well as the scientific world growing more and more into accord with the views I have maintained, and which were at first so vehemently opposed.

I owe so much to the literary men of the English tongue on both sides of the Atlantic, that I shall be glad if, through the devoted labors of the translator, I am enabled to pay them a tribute of gratitude by aiding them in clearing the way for thought in these much disputed fields, or in reconciling in their minds the conflict between faith and science.

R. S.

SCHOeNTHAL, WUeRTEMBERG, September, 1882.

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It is well known that Mr. Darwin's theory on the Origin of Species has been accepted in Germany more widely, with more absolute faith, and with more vehement enthusiasm, than in the country of its birth. In Germany, more conspicuously than elsewhere, it has itself become the subject of developments as strange and as aberrant as any which it assumes in the history of Organic Life. The most extravagant conclusions have been drawn from it—invading every branch of human thought, in Science, in Philosophy, and in Religion. These conclusions have been preached, too, with a dogmatism as angry and as intolerant as any of the old theologies. It is the fate of every idea which is new and fruitful, that it is ridden to the death by excited novices. We can not be surprised if this fate has overtaken the idea that all existing animal forms have had their ancestry in other forms which exist no longer, and have been derived from these by ordinary generation through countless stages of descent. Although this is an idea which, whether true or not, is entirely subordinate to the larger idea of creation, it usurps in many minds the character of a substitute. This is natural enough. The theory, or at least the language, of Evolutionists, puts forward a visible order of phenomena as a complete and all-sufficient account of its own origin and cause. However unsatisfactory this may be to the higher faculties of the mind, it is eminently {6} satisfactory to those other faculties which are lower in the scale. It dismisses as needless, or it postpones indefinitely, all thought of the agencies which are ultimate and unseen. Just as in the physical world, some trivial object which is very near us may shut out the whole of a wide horizon, so in the intellectual world, some coarse mechanical conception may shut out all the kingdom of Nature and the glory of it.

Two great subjects of investigation lie before us. The first is to ascertain how far the Theory of Evolution represents an universal fact, or only one very partial and fragmentary aspect of a great variety of facts connected with the origin and development of Organic Life. The second and by far the most important inquiry, is to estimate aright, or as nearly as we can, the relative place and importance of these facts in the Philosophy of Nature.

Subjects of investigation so rich and manifold as these may well attract all the most varied gifts of the human mind. This they have already done, and there is every indication that they will continue to do so for generations yet to be. Already an immense literature is devoted to them; and every fresh effort of observation and of reasoning seems to open out new and fruitful avenues of thought. The work which is here introduced to the English reader contains an excellent review of this literature, so far as it is represented in the English and German languages. Knowing the author personally, as I have done for many years, I recognize with pleasure in his work all the carefulness of inquiry, and all the conscientiousness of reasoning, which belong to a singularly candid and patient mind.



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The consideration which this work has received from the leaders of religious and philosophic thought in Germany, and, indeed, wherever it has been read in its original form, has led the translator to believe that an English version of it would be acceptable. Especially in America, where religious problems and religious thought are so intimately connected with the processes of scientific and philosophic investigation, and where the agitation of these problems is so peculiarly active and violent, it has seemed that a work marked by so much scholarship, profundity, and comprehensiveness and originality of treatment, must serve an important purpose to the cause of religious no less than of scientific truth. It may be explained here, that the author resided for some years in the family of the Duke of Argyll, and there breathed, to a certain extent, the scientific air of Darwinism in its very origin; and thus his familiarity with all the results of modern scientific research, added to his theological and philosophical acquirements, enable him, with a most admirable blending of the spirit of fairness and toleration with logical severity of treatment, to bring these different domains into their proper relation with each other and to establish between them that essential harmony in which consists the solution of these most profound and vital problems of man's welfare.

Of the translation it may properly be said that, while the aim has been to give the work the clearest possible form consistent with that strict fidelity to the original which is {8} especially demanded by the character of its material, the translator has not hoped to make the work altogether "easy" reading. Peculiarities of the author's style have been, it is believed, largely preserved; and occasional difficulties of apprehension are no doubt to be expected, both from the method of treatment and from the profound and abstruse character of the topics treated. The translator will be well satisfied if it shall be found that he has succeeded in performing his task without adding unduly to the seeming obscurities of certain passages—obscurities which, however, will no doubt vanish before that degree of mental application without which such works may not be read at all intelligibly.

Acknowledgments are properly due and are gladly rendered to George C. Dawson, Esq., of Chicago, and to Mr. Francis F. Browne, editor of The Dial, for valuable assistance in revising and perfecting this version.

G. A. Z.

CHICAGO, October, 1882.

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The Scientific Problem, ... 23



Sec.1. Direct Predecessors, ... 30 Sec.2. Indirect Preparations, ... 33



Sec.1. Darwin, ... 38 Sec.2. The Followers of Darwin.—Ernst Haeckel, ... 45 Sec.3. Modifications of the Theory.—Moriz Wagner. Wigand, ... 52



Sec.1. The Theory of Descent, ... 61 Sec.2. The Theory of Evolution.—Archaeology, Ethnography, Philology, ... 77 Sec.3. The Theory of Selection, ... 100



The Philosophic Problems, ... 108



Sec.1. The Origin of Self-Consciousness and of Free Moral Self-Determination, ... 115 Sec.2. The Origin of Sensation and of Consciousness, ... 127 Sec.3. The Origin of Life, ... 132 Sec.4. The Elements of the World; the Theory of Atoms, and the Mechanical View of the World, ... 140



Sec.1. Elimination of the Idea of Design in the World.—Monism, ... 158




Plan of Treatment, ... 185




Sec.1. Extreme Negation: L. Buechner and Consistent Materialism, ... 188 Sec.2. Replacement of Religion Through a Religious Worship of the Universe.—Strauss. Oskar Schmidt. Haeckel, ... 190 Sec.3. Pious Renunciation of the Knowability of God. Wilhelm Bleek. Albert Lange. Herbert Spencer, ... 193 Sec.4. Spinoza and Hegel in the Garb of Darwin.—Carneri, Ed. von Hartmann, ... 203 Sec.5. Reecho of Negation on the Side of the Christian View of the World, ... 206



Sec.1. Heinrich Lang. Friedrich Vischer. Gustav Jaeger, ... 210



Sec.1. Darwin. Wallace. Owen. Asa Gray. Mivart. McCosh. Anderson. K. E. von Baer. Alexander Braun. Braubach, and others, ... 217



Preliminary View, ... 228



Sec.1. Objections to Darwinism from an Ethical Standpoint, ... 230



Sec.1. The Materialists and Monists. Darwin and the English Utilitarians. Gustav Jaeger, ... 233



Sec.1. Mivart. Alexander Braun, and others, ... 245


Preliminary View, ... 249




a. The Position of Purely Scientific Darwinism in Reference to Theism.

Sec.1. Scientific Investigation and Theism.—The Idea of Creation, ... 252 {13} Sec.2. The Descent Theory and Theism, ... 259 Sec.3. The Evolution Theory and Theism, ... 263 Sec.4. The Selection Theory and Theism, ... 270

b. The Darwinistic Philosophies in their Position Regarding Theism.

Sec.5. The Naturo-Philosophic Supplements of Darwinism and Theism, ... 273 Sec.6. Elimination of the Idea of Design, or its Acknowledgment and Theism, ... 284



Sec.1. The Creation of the World, ... 290 Sec.2. The Creation of Man, ... 314 Sec.3. The Primitive Condition of Man.—Paradise, the Fall of Man, and Primitive History, ... 321 Sec.4. Providence, Hearing of Prayer, and Miracles, ... 345 Sec.5. The Redeemer and the Redemption, the Kingdom of God, and the Receiving of Salvation, ... 373 Sec.6. Eschatology, ... 375




Sec.1. Darwinistic Naturalism and Moral Principles, ... 379 Sec.2. Scientific Darwinism and Moral Principles, ... 386



Sec.1. Darwinistic Naturalism and Moral Life, ... 391 Sec.2. Scientific Naturalism and Moral Life, ... 396


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Agassiz, Louis, 35, 37, 50, 320. Anderson, 225. Anonymus, "the Unconscious," etc., 128, 129, 131, 134, 159. Anonymus, "Vestiges," etc., 33. Argyll, Duke of, 50, 91, 92, 135, 172, 202, 288. Ausland, 159, 240, 281.

Baer, Karl Ernst von, 36, 54, 56, 71, 74, 81, 83, 106, 132, 149, 160, 177, 226, 259, 281, 288, 320. Barrande, 54. Baumgaertner, Heinrich, 57, 176. Blanchard, Emil, 54, 106. Bleek, Wilhelm, 17, 96, 97, 194, 197, 234, 236. Boerhave, 36. Braubach, 226. Braun, Alexander, 55, 176, 226, 246, 397. Braun, Julius, 17. Buch, Leopold von, 52. Buckle, 17. Buechner, Ludwig, 42, 118, 141, 158, 188, 205, 219, 233, 396. Buffon, 31.

Carneri, 203, 238. Carns, 36. Christy, 90. Condillac, 96. Cotta, Bernhard von, 51. Curtius, 96. Cuvier, 31, 32, 34, 37, 320.

Darwin, 17, 18, 25, 27, 38, 118, 171, 177, 217, 240, 320, 389. Descartes, 127. Dillman, 295, 301. Dohrn, 84. DuBois-Reymond, Emil, 124, 125, 127, 130, 134, 149.

Ebrard, 159, 209. Ecker, 56. Escher, von der Linth, 54.

Farrar, 96. Fechner, Gustav Theodor, 135, 146. Fichte, Immanuel Hermann, 142, 175. Fraas, Oskar, 55, 90. Frohschammer, 175.

Gegenbaur, 56. Geiger, Lazar, 17, 96. Geoffrey St. Hilaire, Etienne, 32, 34. Gerhard, 197. Giebel, 54. Goeppert, 54. Goethe, 33, 34, 35, 320. Gray, Asa, 222. Grusebach, 55. Grimm, Jacob, 17, 95.

Haeckel, 35, 42, 43, 45, 75, 78, 106, 123, 130, 133, 149, 159, 160, 166, 170, 204, 219, 234, 237, 281, 395. Hartmann, Eduard von, 56, 60, 106, 131, 142, 168, 176, 191, 205, 334, 376. Heer, Oswald, 56, 176. Hegel, 126, 136, 204. Helmholtz, 136, 159. Heyse, 96. Hilgendorf, 82. His, Wilhelm, 56, 81, 106. Huber, 175. Humboldt, Wilhelm von, 17, 95. Huxley, Thomas, 42, 50, 177, 198, 222, 279.

Jaeger, Gustav, 51, 124, 214, 243. Jellinghaus, 94.

{15} Kant, 195, 282. Keim, 18, 337. Koelliker, 56, 81, 176. Koestlin, Julius, 175, 187. Koestlin, Otto. 149. Kowalewsky, A., 42. Kowalewsky, W., 83. Kurz, Johann Heinrich, 306.

Lamarck, 27, 30, 31, 33, 320. Lang, Heinrich, 197, 210. Lange, Friedrich Albert, 112, 168, 173, 176, 194, 196. Lartet, 96. Leibnitz, 127, 217. Leidy, 83. Lessing, 405, 407. Linnaeus, 30. Livingstone, 93. Lotze, 142, 145, 149. Lubbock, Sir John, 18, 91, 93, 242. Lyell, Sir Charles, 18, 36, 55, 89, 90, 222.

Maedler, 177, 252. Malthus, 39. Marsh, 83. Martensen, 187. Mayer, Robert von, 37, 129, 149, 155. McCosh, 224. Mill, John Stuart, 242. Mivart, 55, 106, 223, 245. Moleschott, 42. Mueller, Fritz, 79. Mueller, Max, 18, 96, 98. Murchison, Sir Roderick, 54.

Naegeli, 56. Nitzsch, Karl Immanuel, 361. Noire, Ludwig, 281.

Oken, 34, 320. Owen, Richard, 35, 56, 164, 176, 221, 223, 320.

Peschel, Oskar, 279. Pfaff, 54. Pfleiderer, Otto, 187. Planck, Carl Ch., 105, 110. Preyer, 136, 146, 153.

Rathke, Heinrich, 81. Reichenbach, 42. Renan, 18. Reville, Albert, 334. Ritschl, 364. Ruetimeyer, 56, 83.

Sandberger, 55, 82. Schaaffhausen, 56, 85, 177. Schelling, 109. Schiller, 180. Schleicher, 17, 96. Schleiden, 42, 51. Schleiermacher, 190. Schmidt, Oskar, 33, 35, 51, 75, 124, 159, 164, 191, 234. Schopenhauer, 128, 190. Schrader, Eberhard, 345. Seidlitz, 51, 159, 238. Semper, Karl, 84, 131. Snell, Karl, 42, 262. Spencer, Herbert, 128, 139, 194, 242, 279. Spinoza, 204. Stael, Madame de, 234. Steffens, 109. Steinthal, 17, 96. Strauss, David Friedrich, 18, 112, 125, 128, 159, 163, 174, 175, 190, 213, 234, 337, 376, 394. Swammerdam, 36.

Tait, 138. Thomson, Sir William, 138. Truempelmann, 209. Tuebingen School, 18. Tylor, 91.

Ulrici, 142, 144, 149, 175, 235.

Virchow, 56, 85. Vischer, Friedrich, 175, 176, 213, 264. Vogt, Karl, 42, 56. Volkmann, A. W., 56, 105, 177.

Wagner, Moriz, 52, 56. Wallace, Alfred Russell, 37, 101, 177, 221, 262. Wedgewood, 96. Weismann, 56. Wigand, Albert, 26, 52, 56, 57, 106, 135, 149, 170, 226. Wundt, 142. Wuertemberger, 82.

Zittel, 56. Zoellner, 128, 129, 131, 138, 139.

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With the appearance of Darwin's "Origin of Species," on the 24th of November, 1859, a new impulse began in the intellectual movement of our generation. It is true, the whole theory advocated and inaugurated by Darwin is, in the first place, only one of the many links in the long chain of phenomena in the realm of the intellectual development of our century, all of which have the same character, and give their stamp to the entire mental work of the last decades. This stamp consists in the tendency of science, which has nearly become universal, not only to consider all phenomena, both of the physical and the mental life, in connection with their preceding conditions in space and time, but to trace them back more or less exclusively to these conditions, and to explain them exclusively by means of the same. What a Wilhelm von Humboldt, and, still more, a Jacob Grimm, prepared the way for in the realm of philology, a Lazar Geiger and a Steinthal, and (under direct influence of Darwin) a Schleicher and a Wilhelm Bleek further developed; what Julius Braun did in the realm of the history of art; what a Buckle and a Sir {18} John Lubbock tried to do in the realm of the history of civilization; what a Max Mueller did in the realm of the history of religion; what the Tuebingen School began and its disciples carried out in the realm of the exegesis of the Bible; what a Strauss and a Renan, and in a certain sense also a Keim, did in the realm of christology; what, finally—without being so closely connected with individual names—was also done in the realm of the world's history: this, Darwin did in the realm of the history of the organic kingdoms, seconded by the geological principles of Sir Charles Lyell and by the investigations in biology and comparative anatomy of a number of scientists. From this point of view, the movement which was inaugurated by Darwin seems to us but the reflex of the universal spirit of the present time upon a particular realm; namely, that of natural science. But since, soon after the appearance of the before-mentioned work and long before the publication of Darwin's "Descent of Man," man also was included in the consequences of the evolution theory, and his existence was explained as a wholly natural development out of lower animal forms; since Darwin himself unreservedly adopted this theory of the descent of man from the animal world as an entirely natural consequence of his doctrine of the origin of species, the evolution question has gone far beyond the proportionately narrow and limited bounds of natural philosophy and of merely theoretical scientific interest—has surpassed in interest all the before-mentioned investigations, however lively this interest was and is to-day, and has stirred up the minds of all most thoroughly, not only in their scientific but also in their religious and ethical depths, some in {19} acknowledgment and admiration, others in aversion and repugnance, and only a few in sober and unprejudiced judgment. While some see in Darwinism the flambeau which now lights mankind to entirely new paths of truth, and also to spiritual and moral perfection, others see in it only an unproved hypothesis, threatening to become the torch which might change the noblest and greatest acquirements of the culture of past centuries into a heap of ashes; while some date from it a new period of culture, others see in it a deep descent of the present from the scientific, religious, and moral height which mankind has ascended.

Under these circumstances, it has become an impossibility for religion and the moral interest as guardians of the highest and most sacred acquisitions of mankind, and still more for theology and ethics as the scientific representations of religion and morality, to remain idle spectators. It would certainly be more agreeable to them, and more profitable, if they could delay their judgment until the question became better cleared up. For the whole question presented by Darwin has not yet passed beyond the stage of problems and attempts at solution; and there is always something unsatisfactory in being compelled to deal with theories which in their fundamentals are still hypotheses. But since all tendencies of the present which are hostile to Christianity and to the theistic view of the world, from the most extreme materialism up to the most sublime monism (as pantheism and materialism of to-day have begun to call themselves), seemingly with the confidence of complete victory, take possession of Darwinism as the solid ground from which they hope to destroy all and every belief {20} connected with faith in a living creator and master of the world, it has also become impossible for those to whom the religious and ethical acquisitions of mankind are a sacred sanctuary to take any longer a reserved and expectant position. Silence now would be looked upon only as an inglorious retreat; and thus nothing remains but openly to face the question: What position must religion and morality take in reference to the Darwinian theories?

In order to treat of the question with that objectivity which it requires, we have to begin with a synopsis of the theories themselves. In this representation we have to discriminate strictly between the merely scientific theories and the naturo-philosophical and metaphysical supplements and conclusions which have been brought into connection with them. For precisely in the mixing of the most different problems which are to be considered here, lies the main cause of the confused and superficial judgment which is so often heard upon these questions.

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The interesting problem which underlies Mr. Darwin's theories is the answer to the question: How did the different species of organic beings on the earth originate? We find ourselves in the midst of an endless variety of organic beings, animals and plants; we see ourselves, so far as regards the entire physical part of our being, in relationship with this organic world—especially with the organization and physical functions of the animal body. The organic individuals come and go. They originate by being begotten by and born of individuals of the same kind, or they spring up through the formation of germs and buds; and they produce in the same way new individuals, that resemble them in all essential characteristics. Like always begets like, so far as our observations go. But not only the individuals, but even the species to which they belong, must have originated at some definite period of time—and, indeed, as geology tells us, not all at once, but in a long series, which stretched through immeasurable epochs of the earth's history. Thus we come face to face with the question, already put, which we can now formulate more {24} precisely: How did the first individuals of each organic species come into existence?

No human being ever has observed, nor ever could observe, the origination of a new species, because man, as it seems, did not appear on the earth until all the other organisms were in existence. For this reason, the scientists for a long time thought it unprofitable to occupy themselves with this question; and even in our time a great many of them declare the question to be absolutely insolvable, and every attempt at answering it to be an unjustifiable use of hypotheses. But the impulse toward investigation admits of no limitation so long as there is any probability of extending its field of action. Especially in the province of nature, so many things which could not be discovered by mere observation have been traced indirectly, and so many important and established facts have been added to our stores of knowledge, by first starting from hypothetical premises, that man has again and again endeavored to approximate an answer to the question of the origin of species by taking the indirect course of hypothesis and induction, whenever the direct way of observation did not lead to any result. Religion of course gives a solution to the problem by stating that the species have been originated by the creative act of God. It is wrong to say that this solution is opposed to the above-mentioned impulse toward investigation; for this solution suffices for religion, whether a natural progress in the origination of species be established or not. For, to the believer in religion, the whole universe, with all its objective phenomena and growth, is the work of God as well as the individuals of the already existing species; and a {25} closer acquaintance with the manner of their origin is not only no disturbance to his ground of belief, but, on the contrary, an addition to his knowledge of the method of God's action. In every man of sound mind, the religious faith is not antagonistic or even indifferent to the scientific impulse toward investigation, but stands upon a most intimate footing with it. Hence the human intellect again and again makes the attempt to find an answer to the problem of the origin of species in a scientific way, and each endeavor of this kind necessarily ends with the dilemma that either the first individuals of a species, no matter whether it be the highest or the lowest, have been evolved out of inorganic matter, or they originated by descent from the most closely related species of their predecessors. The denial of the first part of our dilemma, and the affirmation of the second, is the "Theory of Descent."

But this theory of descent leads us at once into another dilemma. If the species originated by descent from the most closely related lower species, and under certain circumstances also from species of the same rank, and even by degeneration from the next higher, it must have occurred in one of two ways: either by leaps—called by naturalists "metamorphosis of germs" or "heterogenetic conception"—or by a succession of imperceptibly small alterations of the individuals from generation to generation. Each of these changes would have been no greater than the differences we observe to-day between the individuals of the very same species, but became in the course of time so massed and strengthened in one direction that new species have been evolved. This hypothesis is called the "Theory of Development," {26} or "Evolution." We retain this name, although well aware of the fact that the authors do not agree in their use of the term "evolution." Professor Wigand, who adopts only the theory of a descent from one primordial cell to another, and who positively rejects the idea of a progress from one fully developed species to another, claims among other things that one value of his own theory is that he secures for the idea of evolution its full meaning. The expression still has a meaning for those who reject the real descent of the species or their primordial germs one from another, and acknowledge only the ideal bond of a common plan in their successive manifestations. But as soon as we examine more closely the literal and logical meaning of the word, we shall find it of most weight when we understand by it the before-mentioned gradual evolution in opposition to the theory of progress by leaps or new creations. Moreover, it is well known that long before this no other term than evolution was used to designate the growth of a single organic individual from the primordial cell and egg to its fully developed form and vital function. Besides, we find ourselves also in harmony with most of the authors, so far as they have distinct conceptions of the different scientific problems, if we use the term "theory of evolution" for the gradual development of one species from another, in opposition to the hypothesis of a metamorphosis of germs, or even of a genealogy of primordial cells.

But each evolution theory leads again to new theories, as soon as it has to be proved in a scientific way. For it can claim a scientific worth only when sustained by earnest attempts to find and prove the {27} productive power, agencies and laws of such an evolution of species. Those attempts can be made in various ways. As a philosophical question, many attempts at solution have been made, both in ancient and modern times; but being mainly in the realm of metaphysics, they do not come within the limits of our scientific essay. As a question for investigators of natural phenomena, only two attempts of sufficient importance to be mentioned have been made. The first one was made by Lamarck, who, taking the really different ideas of descent and evolution as one, made use of the hypothesis of transmutation; thus becoming the pioneer of Darwinism. The other attempt was made by Darwin in his theory of natural selection, or struggle, for existence, and is called the "Theory of Selection."

In defining our problem, therefore, we find ourselves under the influence of a scientific law of development. The simple problem which we started from has developed into a trinity of problems and attempts at solution. The simple question of the origin of species led us into the dilemma of a generatio aequivoca, or a descent; the hypothesis of a descent led to the dilemma of a heterogenetic conception, or an evolution; and the hypothesis of an evolution rendered necessary the attempt at explaining this evolution, and showed Darwin's method of explaining it by his selection theory. It will be well for the reader to keep distinctly in mind the difference between these problems and theories, in following our investigations, even if we cannot arrange our historical sketch according to the natural principle of division arising from these differences.

For it lies in the nature of the question itself, that {28} these theories, in their historical progress, did not appear singly, but together. Those who inclined to the theory of a descent of species could claim for it the attention of scientific investigators only after having also made the attempt at conceiving this descent in a concrete way, and according to certain analogies of observation. The only analogy of the kind appeared in the sphere of individual development and individual differences on the one hand, and in that of closely related characters of allied species on the other; and thus led of itself to the evolution theory. As soon as the naturalists thought they had found the causes of such an evolution of the species, they naturally placed these causes in the foreground of their demonstrations, and erected upon them the structure of their entire theory; thus treating descent, evolution and selection as one single and indissolubly connected theory. But this manner of treating the question had also its dangers, which have already caused a great deal of confusion and misunderstanding, as well as much unprofitable controversy. Often friends and enemies of the theories placed that which was in favor of the theory of descent to the credit of the evolution or selection theory; and, on the other hand, that which seemed opposed to the selection theory was often held to be a weakening of the evolution and descent theory; and this was done, not only by amateurs, but often enough by the highest authorities also. In reality, however, it is quite conceivable that the idea of a descent may prove correct, and possibly the idea of an evolution of the species will have to be replaced by that of a heterogenetic generation, or by the theory that certain groups in the organic system are originated {29} by heterogenetic generation, and others by evolution; and so the evolution theory must share with the theory of heterogenetic generation, or of a metamorphosis of germs. On the other hand, it is conceivable that even where the evolution theory is confirmed, the evolution can be accounted for wholly or partly by other reasons than those derived from the selection theory. And even this result of present investigations is not inconceivable: that the reasons for and against the different theories will be found to balance one another to such a degree that they will sooner or later lead science, in answering the question of the origin of species, to the old confession of Socrates—"Ignoramus."

We shall, therefore, have to arrange our historical sketch according to the historical order of the appearance of the theories, and treat the problems more or less as an undivided whole. But we shall keep in mind, during our historical sketch, not only the logical separation of the problems in question, in order not to lose clearness of judgment, but we shall also at the end of our review, if we consider the present condition of the problems, have to examine the same once more in detail, so far as regards the above mentioned separation.

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Sec. 1. Direct Predecessors.—Lamarck.

The first man who gave direct expression to the idea of a successive generation of the species through transmutation, and who attempted to follow it up in a scientific way, was the French naturalist and philosopher, Jean Lamarck, born 1744. In the year 1801, and subsequently, he published his views, first in smaller essays and afterward more in detail in his "Philosophie Zoologique," which appeared in 1809, and in the first volume of his "Histoire Naturelle des Animaux sans Vertebres," published in 1815. In these works Lamarck upholds fully the descent and evolution theory, and maintains that the simplest organisms are generated through a generatio spontanea, which is still taking place; but that all the more developed organisms, including man, are descended through a gradual change from other species. With this theory, he put himself in direct and conscious opposition to the old doctrine of the immutability of species and their characteristics, which had been ably maintained by Linnaeus, and also made some attempts at explanation which approach very nearly the selection theory. A change in the physical conditions of life, especially the force of habit in the use or disuse of the organs, the inheritance of physical and psychical {31} qualities thus attained, and the extension of the process of transmutation into extraordinarily long periods of time with very slight changes, are also, in his view, the probable causes of the variation and development of the species. He only lacks the idea of a natural selection in the struggle for existence, and the comparison of the processes in nature with the methodical selection of man in the breeding of domestic animals and plants, to identify his views with those of Darwin.

At first, Lamarck met only with violent opposition; but after a little while his views ceased to attract attention. The time had not yet come to make such an attempt at observing nature from the standpoint of evolution. The sciences which favor such a mode of observation, and even demand it—such as comparative anatomy and physiology and the history of the development of the different plants and animals—were only in their infancy, or were—like palaeontology and the comparative geography of plants and animals—not yet in existence. The influence of Linnaeus, whose views diametrically opposed those of Lamarck, predominated over all the investigations of natural science; Buffon, who favored the ideas of Lamarck, and loved to trace a unity in natural phenomena, was too instable in his investigations and views to arrive at a comprehensive principle; and even the eminent naturalist, Cuvier, of Montpellier, showed in his observation of nature a predilection for analysis rather than synthesis, and although his comprehensive mind inclined to generalize and explain, he placed himself in decided opposition to a theory which was founded only on a few decisive facts.

This last mentioned deficiency seems to have been {32} the main cause of Lamarck's views soon being lost sight of. They nowhere found a support in facts; the force of habit played in them an exaggerated and unnatural role; the different illustrations of them—such as the long neck of the giraffe explained by the permanent and inherited habit of browsing on the branches of high trees, or the web on the toes of frogs, swimming-birds, etc., explained by the habit of swimming—were talked about and laughed at more as curiosities than as worthy of serious consideration.

Only twice after this did the question put by Lamarck attract wider attention from the learned world. The first time was when, in 1830, the bitter contest arose at the Academy of Paris, between Cuvier and Etienne Geoffrey St. Hilaire, the father of Isidor G. St. Hilaire. Geoffrey St. Hilaire had views similar to Lamarck's, but reached them from quite a different standpoint—from the observation of the analogy and homology of the organs; and accounted for the variation of species, not by the use or disuse of the organs, but on the one hand by the common original type of the organs, and on the other by the varied influence of the surroundings—the monde ambiant. Lamarck himself seems not to have been mentioned in this contest. The controversy turned much more on the question whether in observing nature we can proceed by synthesis and find in the analogies of the organisms the principles for explaining the real connection between the different organic forms, or whether the analytical process is the only correct one, and the synthetical should be discarded. The solution of it will probably be, that the one process must be supplemented by the {33} other, as Goethe has already shown in his account of this controversy; but at that time it was decided in favor of the analytical principle, and the question was for the time dropped. It came up for a second time, but created little excitement, in 1844, when an anonymous work, "Vestiges of the Natural History of Creation," directed the attention and the interest of scientists again to Lamarck and his doctrine. But this interest also soon came to an end, until through Darwin's first publication the half-forgotten man again suddenly attained great honor.

Those who wish to form a closer acquaintance with the different advocates of the evolution theory before Darwin's appearance, will find them carefully arranged in the historical sketch which Darwin gives in the introduction to his work on "The Origin of Species"; and the most important extracts of Lamarck's "Philosophie Zoologique" are to be found in Oscar Schmidt's "Descent and Darwinism."[1]

Sec. 2. Indirect Preparations.

While thus the ideas of Lamarck gradually fell into partial oblivion, yet contemporaneous with and following them arose several other series of thoughts, views, and investigations, which, although they only indirectly prepared for the revival of the evolution theory, yet exercised a deeper and more lasting influence on the minds of scientists. We refer to the ideas in regard to natural phenomena held during the first decades of our century; further, to the principles of comparative anatomy which, up to the present time, partly dependent {34} and partly independent of natural philosophy, have been expressed, valued, and admired as leading thoughts; and, lastly, to the empiric results of comparative anatomical and biological investigations in palaeontology and geology, as attained by the help of those very principles. And even physics and astronomy had to cooeperate in preparing the way for the idea of evolution.

The philosophical ideas referred to, together with the points of view and results of comparative anatomy, led more and more decisively to the idea of an original form, or type, which retains its identity in all the modifications of form in plants and animals; and of a ground-plan, which is realized in the systems of the plant and animal world in higher and higher differentiations and in more and more developed modifications, diverging farther and farther from the prototype until it reaches its highest form, still reducible to the prototypes, in the most highly organized dicotyledons in plants, and in the animal world in the mammalia, and lastly in man.

Men like Cuvier and Geoffrey St. Hilaire, who otherwise stand diametrically opposed to each other, unite in these and kindred ideas. The naturalist Oken attains the same result, tinged with the views of Schelling; the poet Goethe, from an intuitive knowledge of nature, arrived at the same conclusion. The former, during a journey in the Hartz Mountains, at the sight of a bleached deer's skull, and the latter, upon picking up a sheep's skull in the Jewish cemetery at Venice, were struck by the same thought: the skull is only a modified vertebra. Oken founded upon this idea and kindred analogies his profound philosophy of the system of animals and plants which comes very near to the evolution {35} theory, and in his cosmogony traces all organisms to a protoplasm in such a way as to bring him in this respect also very near to Darwinism. Goethe, in his metamorphosis of plants, develops ideas in which, in all seriousness, he makes a concrete application of his thought of a prototype to the leaf of a plant; and proved for zooelogy the fruitfulness of his idea of a type by his well known discovery of the mid-jaw bone in man. Although Oscar Schmidt seems to be decidedly right in supposing, in opposition to Ernst Haeckel, that Goethe did not intend to have his idea of unity and development taken in a real but in an ideal sense, and hence could not be called a direct representative of the evolution theory, still he is all the more decidedly a predecessor of that theory in directing attention to the unity in plan and metamorphosis of plants and animals. Louis Agassiz, who, on the other hand, continued up to his death in opposition to the entire doctrine of descent, made the idea of types the principle of his whole classification, and said: "Man is the purpose toward which the whole animal creation tends from the first appearance of the first paleozoic fish." Richard Owen, who rejected the selection theory and favored that of descent, published, long before Darwin's appearance, some most interesting results of his anatomical and palaeontological investigations from the point of view of the prototype and its modifications. "Man, from the beginning of organisms, was ideally present upon the earth," is a sentence which we quote from Owen's works.

In short, this ideal momentum in the observation of the organic kingdoms is not only the most beautiful blossom and the ripest fruit of the union between {36} laborious and comprehensive detailed investigations and a generalizing philosophic penetration, but it was also a very efficient preparation of the mind for the evolution problem, so far as the summing up of the organisms under a type and plan is only the ideal reverse of its realistic reduction to a common pedigree.

We have yet to add the investigations in regard to the history of evolution of the single organisms, as well as those in comparative anatomy, which in former centuries were begun by scientists like Swammerdam and Boerhave and carried more nearly to completion by K. E. von Baer, Carus, and others. In reducing all the tissues of plants and animals to one cell, and tracing back also their individual developments to the first differentiation of the simplest cell, they followed out the unity of the plan of the organic kingdoms—which hitherto had been maintained only ideally and proclaimed as a philosophic postulate—farther and deeper into the sphere of empiric reality. We must mention, moreover, the great palaeontological discoveries which, from the first foraminifera of the Cambrian formations up to the historical period of man, showed a great progressive scale in the appearance of the organisms and a very wide relationship between this scale and the natural systems of botany and zooelogy; and, finally, the principles of geology, which, under the leadership of Sir Charles Lyell, starting from the idea of an identity of the powers which were active in former times with those of the present, attempted to explain the most violent of the changes in the earth's crust in former times by causes active to-day. This often explains prodigious effects—such as the elevation and settling of entire mountains {37} and continents—by the constant and related action of the slightest causes and most gradual steps; it opens the perspective into vast epochs of long and numerous geological periods; and sometimes, where scientists like Cuvier and Agassiz have supposed the most complete cataclysms and the most universal revolutions of the globe, there prove to have been only gradual changes with revolutions very partially and locally limited.

Finally, if we take into consideration the grand discoveries which strikingly illustrate the connection in extent and quality between the universe and all its agencies and powers—such as Robert von Mayer's discovery of the conservation of force and of the mechanical equivalent of heat, or the spectrum analysis and the information which it gives us by ever-increasing evidences of the identity of the cosmic and telluric substances—we may venture to say that the scientific and intellectual ground was well prepared for a theory which takes the origin of organisms into this common relationship of the essential unity and development of the universe.

Only one thing more remained to complete the hypothesis offered by Lamarck, of the fact of a development of species by a new and more satisfactory answer to the question as to the manner of their development. The task of answering in a more comprehensive and scientific way the question as to the manner of development has been undertaken by Darwin in his selection theory. Alfred Russell Wallace, who arrived at the same results contemporaneously with and independently of Darwin, has, with praiseworthy modesty, renounced his claim to priority of the discovery, as Darwin had been longer engaged in working out his theories and had begun to collect materials for proof.

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Sec. 1. Darwin.

In order to explain the development of higher species from lower ones in a natural way, Darwin starts from two facts. The first fact is, that all individuals of the same species show, besides their specific similarity, individual differences: a fact which we call the law of individual variability. The other fact is, that each individual inclines to transmit to his offspring all his qualities—not only the characteristics of the species, but also those of the individual: a fact which we call the law of heredity.

To show how the whole basis of explanation of the evolution of one species from another is given in these two facts, Darwin calls attention to the rules according to which the often extraordinarily great varieties of domestic animals and cultivated plants are obtained and preserved; namely, the rules of artificial breeding. The breeder simply selects from a species those individuals having such individual qualities as he wishes to preserve and to increase, and refrains from breeding those individuals which do not possess the characteristics he wants or which possess them only in a small degree. He continues the same process with the next generation; and by the constant and effectual agency of the two {39} before-mentioned laws, he will, after the lapse of a few generations, have breeded a variety in which the characteristics originally belonging only to a single individual have become common and permanent.

It is now important to consider whether nature, in natural selection (whence the name "Selection Theory") does not act unconsciously according to the same rules, and attain the same results, as man with his artificial and intentional selection; and, furthermore, whether she does not reach results which, according to that principle of natural selection, finally explain the origin of all, even of the highest and most complicated organisms, from one single original form or a few original and simplest forms. Darwin finds these questions answered in the affirmative; and arrives at this answer through the following conclusions.

The English political economist Malthus (1766-1834), in his "Essay on the Principles of Population," established a law in regard to the growth of the human race, which may be applied just as well to all the species of the entire organic world: that population tends to increase in a geometrical ratio, although the conditions of life for the individual remain the same or at most increase in an arithmetical ratio. The consequence is that if the species is to be preserved and the individuals of future generations are to continue to find sufficient food and other means for sustaining life, a great many individuals of each generation must perish very early, and even as germ and seed, and only a minority will be preserved and reproduced. This exuberant prodigality of life-germs, of which proportionately only a few are preserved and reproduced, takes place in the plant and {40} animal world in a very marked degree. There a continual struggle for existence prevails; each individual has to get access to his conditions of life by wresting them from a whole series of other individuals of his own or other species; and now the question arises: which individuals will survive in this struggle? which will more probably be preserved and procreate offspring? Evidently, the answer is, those individuals which possess individual characteristics more favorable to the preservation of the individual than those possessed by other individuals. These individual characteristics are transmitted to the next generation. In this there will be again individuals that have in a still higher degree the characteristics thus transmitted and favorable for the preservation of the individual, or that add to these favorable characteristics new characteristics favorable in another direction to the survival of the individual in the struggle for existence. While these individuals, with more probability than the others, are thus preserved and reproduced, they transmit to their offspring not only the old favorable characteristics increased, but also those newly added. Among the favorable individual qualities, Darwin reckons the divergence of character, the perfection of organization, and the law of correlation; the latter, however, can not be explained by natural selection, since according to this law a variation in an organ brings about a corresponding variation in entirely different organs (e.g., cats with white fur and blue eyes are also deaf).

This is natural selection by means of the survival of the fittest in the struggle for existence. Changes in the conditions and surroundings of life, and more or less {41} perfect adaptation of the organisms to the new conditions of form, color, food and habit, are the main causes of those individual variations, the accumulation of which through many generations produces so great effects. If we only have behind us periods long enough to permit us to imagine each step in the development as an extremely small and hardly appreciable one, natural selection offers us not the exclusive but the main means of explaining the evolution of the whole animal and plant world out of one or a few simple organized original forms.

This is the outline of the selection theory, as given by Darwin in 1859, and still retained in all its essentials. It is true, in his work on the origin of man he added as supplemental the sexual to the common natural selection, and made it of special importance for the presentation of the beautiful in nature—for the production of beautiful forms, colors, and tones, and for the development of power and intelligence. And in the same work he said that there are many circumstances of structure which seem to be neither beneficial nor detrimental to the individual, and that to have overlooked this fact was one of his greatest mistakes in his former publications. But for the rest, he maintains the selection theory unchanged, with the single modification that it explains, if not the whole development of the species through descent, at least that which is of most importance in it.

That it was only one step in the course of reasoning to extend the selection theory to the descent of man, was seen by many as soon as Darwin's work on the origin of species was published and began to attract {42} attention; although not a syllable upon this question was presented in this work. Various persons manifested their presentiment or perception according to their point of view—partly by the most violent opposition to the new doctrine, partly by scientific development or modification of their anthropogonic views, partly also by revelling in imagination in the consequences hostile to religious faith which they thought could be drawn from this doctrine. We remind the reader of the itinerant lectures of Karl Vogt about the ape-pedigree of man, and of the echo they found by assent or dissent in press and public; also of Huxley in England, Karl Snell, Schleiden, Reichenbach, and others; of the materialists, L. Buechuer and Moleschott, and of the publications of Ernst Haeckel. Finally, Darwin himself made us fully certain of the importance which from the beginning he had attributed to his theory, by publishing his work on the "Descent of Man," in the year 1870.

In this work he explained the descent of man fully from the before-named principles of the descent, evolution, and selection theories, of which we have given all the essentials in the foregoing presentation. He carefully enumerates everything in the structure of the human body that reminds us of our relationship with the animals—especially those embryonic phenomena and rudimentary organs in man which are still to be found in use and in a more developed state in different animal species, and which led him to imagine our ancestors now with a tail, then with sharp ears, now living in the water, then being hermaphrodites. He reviews the spiritual qualities of man, and finds for them all analogous qualities in the animal world. He finds in his work on {43} "Expression of the Emotions in Man and Animals," published in 1872, new confirmation of the genealogical relationship of both. He looks over the whole course of the zooelogical system and of palaeontological discoveries, and searches for the points where the branches and twigs of the animal pedigree of man must have diverged. To begin with the lowest branches, he thinks the most important divergence took place where the series of vertebrates may have been developed out of the invertebrates. Here he adopts the investigations of A. Kowalewsky, and the deductions of Haeckel founded upon them, concerning the larva of the ascidiae, a genus of marine mollusca of the order tunicata, and sees in a cord, to be found in this larva, most decided relationship to the spine of the lancelet fish or amphioxus, the lowest of all the vertebrates, it being yet doubtful whether it belongs at all to the vertebrates. In the transition that once took place from one species of ascidian larva to a form similar to the lancelet fish, he sees the new branch diverging in the series of vertebrates. Out of the fish he concludes that the amphibia were developed, and out of those the reptilia, out of one of them the marsupialia, and from them the lemurs or half-apes, the representatives of which yet live in Madagascar and the southern part of Asia. From these there branched off on the one side the platyrrhini, or apes with a flat nose, on the new continent; on the other, the catarrhini, or apes with a narrow nose, on the old. Among the ancestor of the last, he searches for the common progenitors, from which again two branches started—on the one hand the ignoble branches of the catarrhine species of apes, always remaining lower in {44} development, to which also belong the anthropomorphous apes, like the orang outang and gibbon in Asia, the gorilla and chimpanzee in Africa; on the other hand, that branch which represents the ascent of animals to man.

The refining agencies which finally raise the animal up to the man are essentially the same that on the lowest scales of the pedigree have caused the development of the lower organisms into the higher, namely: favorable individual variations, inheritance, acclimatization, survival of the fittest in the struggle for existence, natural, and especially, sexual selection. These are, if not the exclusive, still the main agencies which finally led the primate of the earthly creation upon the stage and furnished him with his superior faculties. But it is particularly by means of his social life, and of the forces which determine, transmit, increase and ennoble the various impulses and instincts promoting it, that man has become what he is. Through the need and faculty of reciprocal help, through sexual selection—which of course is a very essential factor of social life—there originated language, and reflection, and all the intellectual qualities; and through these again originated the moral qualities, which are most important in constituting the specific worth of man, and which were finally developed into self-consciousness and free moral responsibility.

But with the description of this attempt to explain more in detail these specific characteristics of man, we leave the ground of pure natural science and enter the region of philosophy, in which we have to take up the {45} question again (in Book II, Ch. I) at the same point where we here leave it.

Sec. 2. The Followers of Darwin.—Ernst Haeckel.

Darwin's theory soon found an enthusiastic corps of followers—on the continent, and especially in Germany, almost more than in his own country. The outlook into an entirely new explanation of the origin of man, and the probable use of this theory for attacks upon faith in a Creator and Master of the world, called wide-spread attention to it; and the theory opened to natural science itself entirely new impulses and paths, and promised the solution of many problems before which it had hitherto been compelled to stand in silence. To be sure, it threatened likewise to allure the mind from the slow but sure ways of solid study to the entertaining but insecure and aimless paths of imagination and hypothesis.

Among all the German followers of Darwin who adopted not only the idea of an origin of species through descent and evolution, but also the explanation of evolution by natural selection, and extended it so as to make the principle of selection of exclusive value, Ernst Haeckel occupies the most prominent rank.

In his "General Morphology," published in 1866, and in his "Natural History of the Creation," the first edition of which appeared in 1868, and finally in his "Anthropogeny"[2] (why he does not say Anthropogony, we are nowhere informed), 1874, this scientist brought the new theory, which had been presented by Darwin in an almost bewildering flood of details, into connection and order, and, analyzing the powers active in natural selection, combined them into an entire system of laws. He {46} at once drew the origin of man also into the course of reasoning on the new theory, and sustained the theory by the discovery of the monera and other low organisms of one cell, as well as by special investigations of the calcareous sponges. For these labors, he was rewarded by the warm and unreserved acknowledgment which Darwin made to him in his work upon the origin of man, which was published subsequently to the "Natural History of the Creation." There Darwin says: "If this work had appeared before my essay had been written, I should probably never have completed it. Almost all the conclusions at which I have arrived, I find confirmed by this naturalist, whose knowledge on many points is much fuller than mine." Haeckel's labors rendered still greater service to the Darwinian theory by dividing the organic world into three kingdoms: the protista kingdom, the vegetable kingdom, and the animal kingdom,—a division which solves in a most simple way the difficulty that was felt more and more of securing for the lowest organisms a place among the animals or plants. He further aided the theory by leaving the choice open to adopt either a uniform or multiform pedigree of the organisms and their kingdoms and classes, and by treating each class under both points of view; and finally, by fascinating experiments to bring before us in detail the hypothetical pedigrees of all classes of organisms from the protista kingdom up to man.

We will try to reproduce briefly the pedigree which is of most interest—the hypothetical pedigree of man. Haeckel divides it into twenty-two stages, eight of them belonging to the series of the invertebrates, and fourteen to that of the vertebrates. On this ladder of {47} twenty-two rounds, he leads us from the lowest form of the living being, in slight and mostly plausible transitions, continually higher and higher, up to man; and makes our steps easy by mentioning at each stage, on the one hand the corresponding state in the embryonic development, on the other the still living creature through which, in his opinion, the former organisms of the corresponding round of the ladder are still represented, and which accordingly has been a creature that remained on its round, while other members of its family have been developed up to man and to many other genera and species.

He begins with the monera, the organisms of the lowest form, discovered by himself, which have not so much as the organic rank of a cell, but are only corpuscules of mucus, without kernel or external covering, called by him cytod, and arising from an organic carbon formation. The lowest and most formless moneron is the bathybius, discovered by Thomas Huxley, a network of recticular mucus, which in the greatest depths of the sea, as far down as 7,000 metres, covers stone fragments and other objects, but are also found in less depths, in the Mediterranean Sea, for instance. From the moneron he proceeds to the amoeba—a simple cell, with a kernel, which still corresponds to the egg of man in its first state. The third stage is formed by the communities of amoebae (synamoebae), corresponding to the mulberry-yolk in the first development of the fecundated egg, and to some still living heaps of amoebae. To the fourth stage he assigns the planaea, corresponding to the embryonic development of an albumen and the planula or ciliated {48} larva. When these ciliated larvae are developed, they contract themselves so as to form a cavity; and this fifth stage—especially important for his theory—he calls gastraea. In this form, he says, the progaster is already developed, and its wall is differentiated for the first time into an animal or dermal layer (ectoblast), and into a vegetative or intestinal layer (hypoblast). At the sixth stage, there branched off the prothelmis, or worms, with the first formations of a nervous system, the simplest organs of sense, the simplest organs for secretion (kidneys) and generation (sexual organs), represented to-day by the gliding worms or turbellaria; as the seventh stage, the soft worms, as he called them at first—the blood worms, or coelomati, as he describes them in his "Anthropogeny"—a purely hypothetical stage, on which a true body-cavity and blood were formed; the eighth stage are the chorda-animals with the beginning of a spinal rod, corresponding to the larva of the ascidiae. At the ninth stage, called the skull-less animals (acrania), and corresponding to the still living lancelet, we enter the series of the vertebrates. The importance of the eighth and ninth stages for the theory, we have already pointed out in our remarks upon Darwin, p. 43. The tenth stage is formed by those low fishes in which the spinal rod is differentiated into the skull—and the vertebral-column, called the single-nostriled animals (monorrhini), and represented by the cyclostoma of today (hag and lampreys). The eleventh stage is formed by the primaeval fish or selachii (sharks); the twelfth by the mud fish, of which there still live the protopterus in Africa, the lepidosiren in the tributaries of the Amazon, and the ceratodus in the swamps of Southern {49} Australia. On the thirteenth stage, there are the gilled amphibians (sozobranchia), proteus and axolotl; on the fourteenth, the tailed amphibians (sozura), newt and salamander; on the fifteenth, the purely hypothetical primaeval amniota or protamnia (amnion is the name given to the chorion which surrounds the germ-water and embryo of the three higher classes of vertebrates) on the sixteenth, the primary mammals (promammalia), to which the present monotremes (ornithorhynchus and echidna) stand nearest; on the seventeenth, the pouched animals or marsupialia; on the eighteenth, the semi-apes or prosimiae (loris and maki); on the nineteenth, the tailed apes, or menocerca (nose-apes and slender-apes, or semnopithecus); on the twentieth, the man-like apes (anthropoides) or tail-less catarrhini (gorilla, chimpanzee, orang outang and gibbon). And now we come to twenty-one—ape-like men or speechless primaeval men (alali)—of whom we are reminded to-day by the deaf, and dumb, the cretins and the microcephali; and number twenty-two is homo sapiens, the man. The Australians and the Papuans are supposed to be the only remaining representatives of his first stage-development. In like manner, Haeckel also gives us the stem-branches of all the types, classes and orders of the organisms, and forms from them a very acceptable hypothetical pedigree; or—if we prefer to suppose a polyphyletic rather than a monophyletic origin of species—hypothetical pedigrees of the whole organic world.

The perspicuity and clearness of Haeckel's deductions, the extent of his knowledge, and the singleness of his aim, to which he makes them all subservient, lend {50} to his works a great charm. But on the other hand we dare not conceal that, even on the ground of explanations belonging purely to natural history, the character of hypothesis is often lost in that of arbitrariness and of the undemonstrable. Even the unlearned in natural science often enough get this impression when reading his works, and will find it confirmed by scientists who not only contradict his assertions in many cases, but disclose plain errors in his drawings—errors, indeed, exclusively in favor of the unity-hypothesis; and in other cases they show that drawings which are given as pictures of the real, represent merely hypothetical opinions. There is especially evident in his works an extremely strong tendency to impress on his hypotheses the character of an established and proved fact, by giving them the alluring name of laws. Entire systems of laws of the selection theory are produced, and all imaginable assertions are also immediately called laws. For example, Huxley, in his anatomical investigations of apes and men, arrives at the conclusion that the differences between the highest and the lowest apes are greater than the differences between the highest apes and man. This purely anatomical comparison, Haeckel calls repeatedly "Huxley's Law." We are well aware that the idea of law is capable of great extension in meaning, and in that respect we can refer to nothing more instructive than the well-meditated inquiry upon this idea in the "Reign of Law" of the Duke of Argyll (London, Strahan & Co.). But if we may venture to call purely anatomical comparisons of this nature laws, such a use of language destroys all logical reasoning; and this mistake appears again in Haeckel's philosophic {51} discussions, of which we shall have to speak hereafter. We shall have to refer also hereafter to an additional embellishment, which Haeckel thinks himself obliged to give to his works—namely, that he makes on every occasion the strongest attacks upon faith in a personal God, a Creator and Lord of the world; that he traces all the motives of human action to self-interest; that he denies the liberty of man and the moral system of the world; that he makes consent to his view of things the criterion of the intellectual development of a man; and that he thinks to render a service to civilization by such a view of the world and of ethics.

In the consequent carrying out of the selection principle as the satisfactory key in explaining the origin of all species and also of man, Haeckel is indeed, in spite of the approval of his works by the British master, more Darwinian than Darwin himself, who expressly refuses to give exclusive value to this theory of explanation. Hence there are among scientists only a few who go with him to this extent. In Germany, aside from the materialists, we only know of Seidlitz and Oskar Schmidt—who in the thirteenth volume of the "International Scientific Series" treats of "The Theory of Descent and Darwinism," and advocates not only the autocracy of the selection theory, but also all the monistic and atheistic consequences which are deduced from it. Perhaps Gustav Jaeger, Schleiden, Bernhard Cotta—at least judging from their earlier publications—should be mentioned as followers of the pure selection theory; although they do not all draw from it the before-mentioned philosophic consequences. On the other hand, the number of those is very great who, although inspired {52} by Darwin to adopt the idea of an origin of species through descent and evolution, yet have more or less modified, laid aside, or entirely refused the very doctrine which is especially new in Darwin's theory—the selection theory. In the following section we shall briefly give an account of them.

Sec. 3. Modifications of the Theory—Moriz Wagner. Wigand.

One of the most prominent objections to the selection theory, which strikes us at once from the standpoint of natural history, is the following: The varieties of a domesticated species, obtained by artificial breeding, are lost, and return to the original wild form of the species as soon as they are crossed long enough with other varieties or are left to themselves and to the crossing with individuals of the original form of their species; and hence we can not see how individual characteristics, even if favorable to the individual, will not be lost again by the crossing which is inevitable in a state of nature, with such individuals as do not possess those characteristics. Besides, it is an established fact, confirmed by all our observations stretching over thousands of years, that the characteristics of species are preserved in spite of all individual modifications, and that this preservation of the characteristics of species has its cause essentially in the free crossing of individuals.

This objection induced Moriz Wagner to take up again an idea already expressed by Leopold von Buch, and to complete the principle of a selection through natural breeding by another, and partly, indeed, to supplant it by the principle of isolation by migration. Isolated individuals, who, from any reason naturally to {53} be accounted for, leave the mass of their fellows, can from the very consequence of this isolation transmit to their offspring common individual characteristics which are not destroyed again by the crossing with other individuals. They will especially fix and transmit these individual characteristics, when they are favorable to them for the conditions of existence in their new place of living, and these individual characteristics will so much the more be increased and developed in a direction favorable to the subsistence of the individuals in their new place of living, as there are more closely connected with this isolation variations in the conditions of existence, in climate, geographical surroundings, food, and so on. He very attractively applies this theory also to the explanation of the origin of man. According to his opinion, even the nearest animal progenitors of man were isolated, and the isolating power was the rise of the great mountains of the Old World, which took place previous to the glacial period. One pair, or perhaps a few pairs, of those progenitors were driven away from the luxurious climate of the torrid zone to the northern half of the globe, and found their return cut off by glaciers and high mountains; in place of a comfortable life on the trees, necessity urged them to gain support from conditions less favorable to existence, and necessity, this mother of so many virtues and achievements, finally made man what he is. In following out these ideas, Moriz Wagner has gradually and more and more decidedly given up the selection theory, and opposed it by sharp criticisms.

This migration or isolation theory also found a degree of favor, but subordinate in its nature. For it {54} can not and will not pretend to solve the main problems. It only tries to explain how the individual variations, already in existence, might have been preserved and perhaps increased, and how new conditions of existence could have roused latent powers; but not how these variations and these powers originated. Just as little is the selection theory able to explain this; but it pretends to do it, and hence we can easily comprehend how during the last few years a constantly increasing number of voices, and more important ones, have been raised against the selection theory. This opposition came not only from those who—like Agassiz, Barrande, Emil Blanchard, Escher von der Linth, Goeppert, Giebel, Sir Roderick Murchison, Pfaff, and others—directly reject each and every idea of descent on account of the difficulty in defending the selection theory; or who—like Karl Ernst von Baer,[3] (the {55} pioneer in the region of the history of individual development), like Oskar Fraas, Griesebach, Sandberger, and others—generally take a more reserved and neutral position, because of the uncertainty of the facts and the inaccessibility of the problems; but it comes especially from those scientists who are inclined to adopt an origin of species through descent and even through development, yet refuse to explain it by the selection principle, and look for the essential cause of the development in the organisms themselves, without claiming to have themselves found these causes. Among the most prominent advocates of this view, we may name the late Sir Charles Lyell, Mivart, and {56} Richard Owen, in England; and in Germany, Alexander Braun, Ecker, Gegenbaur, Oswald Heer, W. His, Naegeli, Ruetimeyer, Schaaffhausen, Virchow, Karl Vogt, A. W. Volkmann, Weismann, Zittel, and here also Moriz Wagner, and among the philosophers, Eduard von Hartmann. Many of these men are but little aware of the difference between the two questions: whether, on the one hand, the adoption of the origin of species through descent does not of itself involve the idea of a gradual development of one species from another, almost unobservable in its single steps; or, on the other hand, whether a descent of species through heterogenetic generation in leaps and through a metamorphosis of the germs, could be imagined. They consider descent and evolution as identical; and this identification is explainable so long as we are not in a condition to come nearer to the eventual causes of the supposed variation of species. But men are not wanting who put these questions clearly and plainly, and separate them distinctly from one another. Among them we may mention K. E. von Baer, Ed. von Hartmann and Wigand; of the latter we will have occasion to speak more in detail hereafter. Among them we find also scientists who answer the question in the sense of a new-modeling of the species, of a heterogenetic generation, and of a metamorphosis of germs. To this class belong especially Oswald Heer—"Urwelt der Schweitz" ("Antediluvian World in Switzerland"), Zuerich, 1865, p. 590-604; Koelliker—"Ueber die Darwin'sche Schoepfungstheorie," ("Darwin's Theory of Creation"), Leipzig, 1864; "Morphologie und Entwicklungeschichte des Pennatulidenstammes nebst allgemeinen Betrachtungen zur Descendenzlehre," {57} ("Morphology and History of the Development of the Stem of the Pennatulidae, together with General Remarks on the Descent Theory"), Frankfurt, 1872; and Heinrich Baumgaertner—"Natur und Gott" ("Nature and God"), Leipzig, Brockhaus, 1870. Heer has introduced into scientific language the term "new-modeling of the species," Koelliker that of a "heterogenetic generation," and Baumgaertner that of a "transmutation of the types through a metamorphosis of germs." Baer also is not averse to adopting the latter.

The botanist, Albert Wigand, of Marburg, takes a peculiar position. On one hand, the observation of the relationship of organic beings with one another leads him to adopt a common genealogy, a descent; on the other, the objections to adopting a descent of the species one from another appear to him insurmountable. In the first place, he sees all the species everywhere strictly limited—although in the second volume of his work, which appeared after the preceding lines were written, he again warns against a one-sided emphasizing of the invariability of species. In the second place, he sees so clearly, through the whole organic world, the differences, nay, the contrasts, of the species, in their building plan, in the numbers and conditions and positions of their parts, and in their mode of development, that it appears to him impossible to assume in the perfected organism a production of germs which in a course of generations, by a process even as gradual as possible, would grow into such an entirely new phenomenon as a new, even closely related, species would be. But if we adopt the theory of a heterogenetic generation, we explain by it the variety but not the similarity of species; {58} for a heterogenetic generation would in the new species make everything different from the old one—a conclusion, the necessity of which it would be difficult to show. For these reasons, he refers the descent of the organic beings, not to the series of the species, with their individuals already specified and defined, but to the series of primordial cells living free in the water. The earliest primordial cells represented only the common character of the whole organic world, and out of them the primordial cells of the animal and those of the vegetable kingdom were produced by dividing the cells; so that the first ones embraced only the general and primitive characteristics of the whole animal, the last ones those of the whole vegetable kingdom. Out of these primordial cells of the two kingdoms, those of the main types proceeded—(for instance, the primordial cells of the radiated animals, the vertebrates, etc., the gymnosperms, the angiosperms, etc.); out of them those of the classes—(for instance, the mammalia, the dicotyledons); out of them those of the orders—(for instance, the beasts of prey, rosiflorae); out of them those of the families (canina, rosaceae); out of them those of the genus (canis, rosa); and out of them those of the species (canis lupus, rosa canina). Only when the primordial cells of the species had been produced, were they developed into finished representatives of the species; and when once these primordial cells of the species had been developed into finished and full-grown individuals of the species, their transmission took place in the manner well known to us. Wigand published his criticism of the Darwinian Theories in his larger work, "Der Darwinismus und die Naturforschung Newtons und Cuviers," ("Darwinism {59} and the Natural Science of Newton and Cuvier"), Braunschweig, Vieweg, Vol. I, 1874, Vol. II, 1876, and his own attempt at explanation in a smaller book, published at the same place in 1872: "Die Genealogie der Urzellen als Loesung des Descendenzproblems oder die Entstehung der Arten ohne natuerliche Zuchtwahl" ("Genealogy of the Primordial Cells as a Solution of the Problem of Descent; or the Origin of Species without Natural Selection").

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