The dynamics of living matter The dynamics of living matter . dynamicsofliving00loeb Year: 1906 LECTURE X HEREDITY * i. THE HEREDITARY EFFECTS OF THE SPERMATOZOON AND EGG IN addition to the developmental effects, the spermatozoon has a hereditary effect, inasmuch as it transmits the paternal qualities to the offspring. The experiments on artificial parthenogenesis or chemical fertilization suggest the possibility that the developmental and the heredi- tary agencies in the spermatozoon are connected with different substances. O. Hertwig twenty years ago denned the process of fertilization as t
The dynamics of living matter The dynamics of living matter . dynamicsofliving00loeb Year: 1906 LECTURE X HEREDITY * i. THE HEREDITARY EFFECTS OF THE SPERMATOZOON AND EGG IN addition to the developmental effects, the spermatozoon has a hereditary effect, inasmuch as it transmits the paternal qualities to the offspring. The experiments on artificial parthenogenesis or chemical fertilization suggest the possibility that the developmental and the heredi- tary agencies in the spermatozoon are connected with different substances. O. Hertwig twenty years ago denned the process of fertilization as the fusion of two nuclei; namely, the egg nucleus and the sperm nucleus. While this fusion is apparently of importance for the hereditary effects, one fails to see how a fusion of two nuclei must cause an egg to develop. The experiments on artificial parthenogenesis indicate clearly enough that the development of the egg can be caused without even the presence of a sperm nucleus. On the other hand, the experiments on merogony show that a fragment of egg protoplasm which has no nucleus can develop when fertilized by a spermatozoon. Delage made extensive experiments in which he cut pieces of protoplasm from the egg of Echinoderms, Annelids, and Mollusks.* These pieces developed when a spermatozoon entered into them. In this case fertilization occurred without a fusion of nuclei, as there was no egg nucleus present. It is a very striking fact that for the first stages of development the hereditary influences of the spermatozoon and the egg are by no means equal. It seems that for these first stages the influence of the egg by far exceeds that of the spermatozoon. It may almost be said that the first stages of the embryo are exclusively or almost exclusively determined by the egg, and not by the spermatozoon. This is best illustrated if we hybridize forms whose first stages of development differ radically from each other, sea urchin and starfish. The pure larvae of both forms g
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