Intracellular pangenesis : including a paper on fertilization and hybridization / by Hugo de Vries ... tr. from the German by C. Stuart Gager.

  • Hugo de Vries
Date:
1910
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Licence: Public Domain Mark

Credit: Intracellular pangenesis : including a paper on fertilization and hybridization / by Hugo de Vries ... tr. from the German by C. Stuart Gager. Source: Wellcome Collection.

Provider: This material has been provided by the Francis A. Countway Library of Medicine, through the Medical Heritage Library. The original may be consulted at the Francis A. Countway Library of Medicine, Harvard Medical School.

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    of reproduction, this, according to Weismann, need not be the case. On the contraiy, from the one-sided differen- tiation of these cells, he beheves that there is a corre- sponding reduction of their germ-plasm. Every somatic cell receives, at the time of its origination, only those hereditary elements which will be needed by itself and its descendents. Against this assumption objections have been raised from different sides, and some of them we shall describe in detail in the Section on cellular pedigrees. Here, how- ever, we must enter into the principal phase of the ques- tion, namely, the relation of the ancillary hypotheses to the main principle of the author. That principle is the assumption of units, of which every one is capable of reproducing all, or at least nearly all, hereditary characters of the species. There is sup- posed to be, for each individual, only one hereditary sub- stance, only one material bearer of the hereditary tenden- cies.^* To be sure, this is composed of ancestral plasms which differ only slightly. A check must necessarily be put to an excessive accumulation of various hereditary tendencies by some kind of an arrangement. But, as we have seen in our first section, the differentiation of the organs demands the divisibility of the units of the germ- plasm, and this in exactly the same high degree that the differences of the individual organs and cells of an or- ganism reach themselves. In the somatic cells the germ- plasm must therefore gradually become divided into those components, and hence, these are the bearers of the in- dividual hereditary characters. Let us continue to build a few moments longer on this conclusion, without reference to the chief assumption. In ^*^Ueher die Zahl der Richtungskorper, p. 29.
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