Herbert Spencer and animal evolution by Bourne Gilbert C. (Gilbert Charles) 1861-1933

Author:Bourne, Gilbert C. (Gilbert Charles), 1861-1933
Language: eng
Format: epub
Tags: Spencer, Herbert, 1820-1903, Evolution
Publisher: Oxford Clarendon Press
Published: 1910-11-13T05:00:00+00:00

under ordinary conditions, would develop into a normal larva or adult.

Arguing from these observations, Driesch constructed an epigenetic theory of development not very different from Herbert Spencer's, and laid down the law that the destiny of every cell in the embryo is a function of its position.

But before this R-oux had shown that if one of the first two blastomeres of a frog's egg is destroyed, the result is, not the formation of a whole embryo of half size, but a half embryo, and further observation and experiment has shown that in whole classes of the animal kingdom the materials necessary for the formation of the different organs of the larva and adult that is to be are already present and localized in the germ-cell, and are dealt out, according to their kind, at every division from the first onwards.

Here I must digress for a moment to explain that Weismann, agreeing in this matter with Strasburger and O. Hertwig, held it as proved that the biophors and the aggregates of biophors forming determinants, are located in the chromosomes of the nucleus of the germ-cell. This view, supported by a number of considerations, seemed to be amply proved by an experiment of Boveri, who fertilized the anucleate fragments of the eggs of one species of sea-urchin with the sperm of another species, and reared larvae which exhibited the paternal characters only. But these results have since been called into question and have quite recently been contradicted by the experiments of Kupelwieser and Loeb, who fertilized the ovum of a sea-urchin with the spermatozoon of a mollusc, and obtained the characteristic larva of the sea-urchin without any trace of paternal characters. And numerous other experiments—too many for me tO' recount now—have shown that, whatever may be the exact role of the nucleus, the cytoplasm of the germ-cell certainly contains organ-forming materials, and that if

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