Problems of fertilization / by Frank Rattray Lillie.

  • Lillie, Frank Rattray, 1870-1947.
Date:
[1919], ©1919
Catalogue details

Licence: Public Domain Mark

Credit: Problems of fertilization / by Frank Rattray Lillie. Source: Wellcome Collection.

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    *99 development might proceed to a late stage. Sooner or later, however, the heterogenic hybrids proved to be non-viable. There is, however, according to Newman, definite evidence of specificity in teleosts in the sense that species fertilization succeeds much more readily than any hybrid fertilization. The percentage of hybrid fer- tilized eggs is always less under given conditions and is frequently extremely small. The more ready union of the species sperm must depend upon some chemical rela- tion between egg and sperm, more highly developed between gametes of the same than between gametes of different species. This obviously operates at the surface, because the subsequent events of fertilization after pene- tration appear to proceed with equal facility whether the sperm belongs to the same or to a different species. Moenkhaus (1910), on the other hand, believes that, in the case of the teleosts studied by him, there is no evi- dence of any specific adaptation of the egg for its own spermatozoon. No adequate test of such a conclusion appears to have been made. The dry method of insemi- nation usually employed for teleosts exposes the egg to the highest possible sperm concentration and thus ren- ders a quantitative examination of the problem of specificity impossible. Moenkhaus (1904), Gunther and Paula Hertwig (1914), and Morris (1914) found normal penetration of the spermatozoon, normal behavior of the germ nuclei, and no evidence of chromatin elimination in the hybrid fertilization of the teleosts that they have studied cyto- iogically. However, Pinney (1918) reports chromatin elimination in certain teleost crosses in the first and