22 



HEREDITY AND SELECTION IN SOCIOLOGY 



divisions (Fig. 3, C, E). The result of the two divisions is the 

 formation of four spermatozoa of equal size find equal capacities, 

 each one of which contains half the number of chromosomes 

 found in the original germ-ceU. 



In the case of parthenogenetic eggs there is usually only one 

 maturation division. The reason for this is not hard to find. 



Pig. 3. — Matukation op Spebmatozoid (afteb Weismaito). 

 {By -permission of Mr. Edward Arnold.) 



A, Primitive germ-cell, with nucleus. B, spermatocyte. C, the first 



karyokinesis. D, result of first karyokinesis. E, the second 



karyoldnesis. P, four spermatozoa of equal size, matured 

 (Sfz = Spermatozoa) . 



The parthenogenetic egg has to retain, not only the hereditary 

 substance of the ovocyte, but also the equivalent of the sperma- 

 tozoon, in view of the fact that it undergoes no fertilisation. 



It is time now to say a word concerning the phenomenon of 

 fertilisation, or amphimixis, which plays so important a role in 

 the animal world. The very fact that fertilisation, or amphi- 



