[ PREFACE] 9
[ INTRODUCTION] 27
[ CHAPTER I.]—The Return to Wigand—The Botanist, Julius von Sachs—The Vienna Zoologist, Dr. Schneider 35
[ CHAPTER II.]—Professor Goethe on "The Present Status of Darwinism"—Explains the Reluctance of certain men of Science to Discard Darwinism 41
[ CHAPTER III.]—Professor Korchinsky Rejects Darwinism—His Theory of Heterogenesis—Professor Haberlandt of Graz—Demonstration of a "Vital Force"—Its Nature—The Sudden Origination of a New Organ—Importance of the Experiment. 49
[ CHAPTER IV.]—Testimony of a Palaeontologist, Professor Steinmann—On Haeckel's Family Trees—The Principle of Multiple Origin—Extinction of the Saurians—"Darwinism Not the Alpha and Omega of the Doctrine of Descent"—Steinmann's Conclusions 60
[ CHAPTER V.]—Eimer's Theory of Organic Growth—Definite Lines of Development—Rejects Darwin's Theory of Fluctuating Variations—Opposes Weismann—Repudiates Darwinian "Mimicry"—Discards the "Romantic" Hypothesis of Sexual Selection—"Transmutation is a Physiological Process, a Phyletic Growth" 69
[ CHAPTER VI.]—Admissions of a Darwinian—Professor von Wagner's Explanation of the Decay of Darwinism—Darwinism Rejects the Inductive Method, Hence Unscientific—Wagner's Contradictory Assertions 90
[ CHAPTER VII.]—Haeckel's Latest Production—His Extreme Modesty—Reception of the Weltraetsel—Schmidt's Apologia—The Romanes Incident—Men of Science Who Convicted Haeckel of Deliberate Fraud 104
[ CHAPTER VIII.]—Grottewitz Writes on "Darwinian Myths"—Darwinism Incapable of Scientific Proof—"The Principle of Gradual Development Certainly Untenable"—"Darwin's Theory of "Chance" a Myth" 118
[ CHAPTER IX.]—Professor Fleischmann of Erlangen—Doctrine of Descent Not Substantiated—Missing Links—"Collapse of Haeckel's Theory"—Descent Hypothesis "Antiquated"—Fleischmann Formerly a Darwinian—Haeckel's Disreputable Methods of Defense 124
[ CHAPTER X.]—Hertwig, the Berlin Anatomist, Protests Against the Materialistic View of Life"—No Empiric Proof of Darwinism—"The Impotence of Natural Selection"—Rejects Haeckel's "Biogenetic Law" 137
[ CONCLUSION.]—Darwinism Abandoned by Men of Science—Supplanted by a Theory in Harmony With Theistic Principles 146

[ ]

PREFACE.

The general tendency of recent scientific literature dealing with the problem of organic evolution may fairly be characterized as distinctly and prevailingly unfavorable to the Darwinian theory of Natural Selection. In the series of chapters herewith offered for the first time to English readers, Dr. Dennert has brought together testimonies which leave no room for doubt about the decadence of the Darwinian theory in the highest scientific circles in Germany. And outside of Germany the same sentiment is shared generally by the leaders of scientific thought. That the popularizers of evolutionary conceptions have any anti-Darwinian tendencies cannot, of course, be for a moment maintained. For who would undertake to popularize what is not novel or striking? But a study of the best scientific literature reveals the fact that the attitude assumed by one of our foremost American zoologists, Professor Thomas Hunt Morgan, in his recent work on "Evolution and Adaptation," is far more general among the leading men of science than is popularly supposed. Professor Morgan's position may be stated thus: He adheres to the general theory of Descent, i.e., he believes the simplest explanation which has yet been offered of the structural similarities between species within the same group, is the hypothesis of a common descent from a parent species. But he emphatically rejects the notion—and this is the quintessence of Darwinism—that the dissimilarities between species have been brought about by the purely mechanical agency of natural selection.

To find out what, precisely, Darwin meant by the term "natural selection" let us turn for a moment, to his great work, The Origin of Species by Means of Natural Selection. In the second chapter of that work, Darwin observes that small "fortuitous" variations in individual organisms, though of small interest to the systematist, are of the "highest importance" for his theory, since these minute variations often confer on the possessor of them, some advantage over his fellows in the quest for the necessaries of life. Thus these chance individual variations become the "first steps" towards slight varieties, which, in turn, lead to sub-species, and, finally, to species. Varieties, in fact, are "incipient species." Hence, small "fortuitous" fluctuating, individual variations—i.e., those which chance to occur without predetermined direction—are the "first-steps" in the origin of species. This is the first element in the Darwinian theory.

In the third chapter of the same work we read: "It has been seen in the last chapter that amongst organic beings in a state of nature there is some individual variability. * * * But the mere existence of individual variability and of some few well-marked varieties, though necessary as a foundation of the work, helps us but little in understanding how species arise in nature. How have all those exquisite adaptations of one part of the organization to another part, and to the conditions of life, and of one organic being to another being, been perfected? * * *" Again it may be asked, how is it that varieties, which I have called incipient species, become ultimately converted into good and distinct species, which in most cases obviously differ from each other far more than do the varieties of the same species? How do those groups of species which constitute what are called distinct genera arise? All of these results follow from the struggle for life. Owing to this struggle, variations, however slight and from whatever cause proceeding, if they be in any degree profitable to the individuals of a species, in their infinitely complex relations to other organic beings, and to their physical conditions of life, will tend to the preservation of such individuals and will generally be inherited by the offspring. The offspring also will thus have a better chance of surviving, for of the many individuals of any species which are periodically born, but a small number can survive. I have called this principle by which each slight variation, if useful, is preserved, by the term, "natural selection." Mr. Darwin adds that his meaning would be more accurately expressed by a phrase of Mr. Spencer's coinage, "Survival of the Fittest."

It may be observed that neither "natural selection" nor "survival of the fittest" gives very accurate expression to the idea which Darwin seems to wish to convey. Natural selection is at best a metaphorical description of a process, and "survival of the fittest" describes the result of that process. Nor shall we find the moving principle of evolution in individual variability unless we choose to regard chance as an efficient agency. Consequently, the only efficient principle conceivably connected with the process is the "struggle for existence;" and even this has only a purely negative function in the origination of species or of adaptations. For, the "surviving fittest" owe nothing more to the struggle for existence than our pensioned veterans owe to the death-dealing bullets which did not hit them. Mr. Darwin has, however, obviated all difficulty regarding precision of terms by the remark that he intended to use his most important term, "struggle for existence" in "a large and metaphorical sense."

We have now seen the second element of Darwinism, namely, the "struggle for life." The theory of natural selection, then, postulates the accumulation of minute "fortuitions" individual modifications, which are useful to the possessor of them, by means of a struggle for life of such a sanguinary nature and of such enormous proportions as to result in the destruction of the overwhelming majority of adult individuals. These are the correlative factors in the process of natural selection.

In view of the popular identification of Darwinism with the doctrine of evolution, on the one hand, and with the theory of struggle for life, on the other hand, it is necessary to insist on the Darwinian conception of small, fluctuating, useful variations as the "first-steps" in the evolutionary process. For, this conception distinguishes Darwinism from the more recent evolutionary theory, e.g., of De Vries who rejects the notion that species have originated by the accumulation of fluctuating variations; and it is quite as essential to the Darwinian theory of natural selection as is the "struggle for life." It is, in fact, an integral element in the selection theory.

The attitude of science towards Darwinism may, therefore, be conveniently summarized in its answer to the following questions: