366 ON THE NUMBER OF POLAR BODIES AND 



uniform distribution of the ancestral germ-plasms, although this does 

 not imply that every ancestral germ-plasm of the mother-nucleus 

 would be represented in each of the two daughter-nuclei. But 

 if out of e. g. eight nuclear loops at the equatorial plane, four pass 

 into one, and the other four into the other daughter-nucleus, each of 

 the latter will contain an equal number of ancestral germ -plasms, 

 although different ones. This is indeed part of the foundation 

 of the theory, for the 'reducing division' must remove exactly 

 half of the original number of ancestral germ-plasms, and pre- 

 cisely the same number must be replaced at a later period by 

 the sperm-nucleus. This could hardly be achieved with sufficient 

 precision by direct nuclear division. 



I now come to inquire whether the expulsion of the second 

 polar body is in reality, as I have already maintained, a reduction 

 in the number of ancestral germ-plasms present in the nucleus of 

 the egg. The view itself is sufficiently obvious, and it would 

 supply an explanation of the meaning of the process which is still 

 greatly wanted ; but it will nevertheless be not entirely useless to 

 consider other possible theories. 



It would be quite conceivable to suppose that the youngest 

 egg-cells, which multiply by division, may undergo one ' reducing 

 division ' in addition to the ordinary process. Of course this 

 should occur once only, for if repeated, the number of ancestral 

 idioplasms in the nucleus of the germ-cell would undergo a decrease 

 greater than could be afterwards compensated by the increase due 

 to fertilization. Thus the number of ancestral germ-plasms would 

 continually decrease in the course of generations, a process which 

 would necessarily end with their complete reduction to a single 

 kind, viz. to the paternal or the maternal germ-plasm. But the 

 occurrence of such a result is disproved by the facts of heredity. 

 Although such an early occurrence of the ' reducing division ' 

 would offer advantages in that nothing would be lost, for both 

 daughter-nuclei would become eggs, instead of one of them being 

 lost as a polar body, nevertheless I do not believe that it really 

 occurs : weighty reasons can be alleged against it. 



Above all, the facts of parthenogenesis are against it. If the 

 number of ancestral germ-plasms received from the parents were 

 reduced to half in the ovary of the young animal, how then could 

 parthenogenetic development ever take place? It is true that 



