The evolution of man: a popular exposition of the principal points of human ontogeny and phylogenyFrom the German of Ernst Haeckel . «a conception w^hich in the present condition of histologicalknowledge seems quite allowable ; for we can even yetdirectly observe this oldest histological process of differ-entiati(>>Ji in Ontogeny. It will be Iemenibcrud that in the THE MONElirLA. ^T eo^g-cell of animals, either before or after fertilization, theoriginal kernel disappeared. We explained this phenomenonas a reversion or atavism, and assumed that the egg-cell,in accordance with the law of l
The evolution of man: a popular exposition of the principal points of human ontogeny and phylogenyFrom the German of Ernst Haeckel . «a conception w^hich in the present condition of histologicalknowledge seems quite allowable ; for we can even yetdirectly observe this oldest histological process of differ-entiati(>>Ji in Ontogeny. It will be Iemenibcrud that in the THE MONElirLA. ^T eo^g-cell of animals, either before or after fertilization, theoriginal kernel disappeared. We explained this phenomenonas a reversion or atavism, and assumed that the egg-cell,in accordance with the law of latent heredity, first fallsback into the kernel-less, cytod stage (Fig. 165). It is on]yafter fertilization is accomplished that a new cell-kernelarises in this cytod, which thus becomes the parent-cell{Cytula, Fig. 1G6). The transitory kernel-less cytod-con-dition, intermediate between the egg-cell and the parent-cell, is an interesting germ-form, because, in accordancewith the fundamental law of Biogeny, it reproduces theoriginal, oldest parent-form of the Moneron; w^e thereforecall it the Monerula. (Cf vol. i. pp. 178-183.). Fig. 1G5.âMonerula of (Rabbit). The fertilized egg-cell afterthe loss or the nucleus is a simple ball of protoplasm (d). The outer coveringof the latter is formed by the modified zona pellucida (z) together witha mucous layer (h) secreted on to the outside of the latter. In this a fews^jerm-cells are still visible (.5). Fig. 166.â (Cytulo) of a Mammal (Eabbit): Tc, parent,kernel; n, nucleolus of the latter; p, protoplasm of the parent-cell; z,modified zona pellucida ; s, sperm-cells ; h, outer albuminou3 covering. 52 THE EVOLUTION OF MAN. We have already explained the one-celled germ-form,wliich we see in the original egg-cell and the parent-cellwhich is originated by the fertilization of the egg-cell, asthe reproduction of a one-celled parent-form, to which weascribed the organization of an Amoeba (cf Chap. VI.). Forthe Amoeba, as
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