United States or Réunion ? Vote for the TOP Country of the Week !
It will be obvious from what has preceded, that we do not agree with Professor Koelliker in thinking the objections which he brings forward so weighty as to be fatal to Darwin's view. But even if the case were otherwise, we should be unable to accept the "Theory of Heterogeneous Generation" which is offered as a substitute. That theory is thus stated:
"Darwin," says Professor Koelliker, "is, in the fullest sense of the word, a Teleologist. And again: "7. The teleological general conception adopted by Darwin is a mistaken one. "Varieties arise irrespectively of the notion of purpose, or of utility, according to general laws of Nature, and may be either useful, or hurtful, or indifferent.
Names of men, like M. Wagner, Naegeli, Wigand, Koelliker, and Kerner mark these attempts; but of these investigators Naegeli alone proposed a well-developed hypothesis. Finally, however, Eimer, professor of zoology in Tuebingen came forward with a detailed theory of Descent.
On the basis of such experiments Korschinsky developed the theory which had been proposed by Koelliker in Wuerzburg thirty years earlier, namely, the theory of "heterogeneous production" or "heterogenesis," as Korschinsky calls it.
In favour of this hypothesis, Professor Koelliker adduces the well-known facts of Agamogenesis, or "alternate generation"; the extreme dissimilarity of the males and females of many animals; and of the males, females, and neuters of those insects which live in colonies: and he defines its relations to the Darwinian theory as follows:
UEBER DIE DARWIN'SCHE SCHOePFUNGSTHEORIE; EIN VORTRAG, Von A. KOeLLIKER. Leipzig, 1864. EXAMINATION DU LIVRE DE M. DARWIN SUR L'ORIGINE DES ESPECES. Par P. FLOURENS. Paris, 1864. In the course of the present year several foreign commentaries upon Mr. Darwin's great work have made their appearance. Darwin's views.
Upon this, Professor Koelliker remarks that the absence of transitional forms in the fossil world, though not necessarily fatal to Darwin's views, weakens his case. The struggle for existence does not take place." To this objection, urged by Pelzeln, Koelliker, very justly, attaches no weight. A tendency of organisms to give rise to useful varieties, and a natural selection, do not exist.
If one accepts saltatory evolution, as for instance, Heer, Koelliker, and Wigand did long ago, then, as Grottewitz now discovers, the difficulty arising for Darwinism from the absence of the numerous intermediary forms which it postulates, naturally disappears. Grottewitz attributes sudden variation to the influence of environment, just as Geoffroy St. Hilaire had already done before Darwin.
Strongly and freely as we have ventured to disagree with Professor Koelliker, we have always done so with regret, and we trust without violating that respect which is due, not only to his scientific eminence and to the careful study which he has devoted to the subject, but to the perfect fairness of his argumentation, and the generous appreciation of the worth of Mr.
On the other hand, this observation plainly proves two things: first, that the above mentioned doctrine of Koelliker, now held by Korschinsky is a move in the right direction for the discovery of the causes of descent; and secondly, that the principal cause of the evolution is not to be sought in environment and blind forces but in the systematically working, internal vital principle in plants and animals.
Word Of The Day