236 THE CONTINUITY OF THE GERM-PLASM AS THE 



been fertilized had the queen been impregnated. The supposition 

 that, at certain times, the queen produces egg's requiring fertiliza- 

 tion, while at other times her eggs develope parthenogenetically, is 

 quite excluded by this experiment ; for it follows from it, that the 

 eggs must all be of precisely the same kind, and that there is no 

 difference between the eggs which require fertilization and those 

 which do not. 



But does it therefore follow that the quantity of germ-plasm 

 in the segmentation nucleus is not the factor which determines 

 the beginning of embryonic development ? I believe not. It 

 can be very well imagined that the nucleus of the egg, having 

 expelled the ovogenetic nucleoplasm, may be increased to the 

 size requisite for the segmentation nucleus in one of two ways : 

 either by conjugation with a sperm-nucleus, or by simply growing 

 to double its size. There is nothing improbable in this latter as- 

 sumption, and one is even inclined to inquire why such growth 

 does not take place in all unfertilized eggs. The true answer to 

 this question must be that nature generally pursues the sexual 

 method of reproduction, and that the only way in which the 

 general occurrence of parthenogenesis could be prevented, was by 

 the production of eggs which remained sterile unless they were 

 fertilized. This was effected by a loss of the capability of growth 

 on the part of the egg-nucleus after it had expelled the ovogenetic 

 nucleoplasm. 



The case of the bee proves in a very striking manner that the 

 difference between eggs which require fertilization, and those which 

 do not, is not produced until after the maturation of the egg, and 

 the removal of the ovogenetic nucleoplasm. The increase in the 

 quantity of the germ-plasm cannot have taken place at any earlier 

 period, or else the nucleus of the egg would always start embryonic 

 development by itself, and the egg would probably be incapable of 

 fertilization. For the relation between egg-nucleus and sperm- 

 " nucleus is obviously based upon the fact that each of them is in- 

 sufficient by itself, and requires completion. If such completion 

 had taken place at an early stage the egg-nucleus would either 

 cease to exercise any attractive force upon the sperm-nucleus, or 

 else conjugation would be effected, as in Fol's interesting experi- 

 ments upon fertilization by many spermatozoa ; and, as in these ex- 

 periments, malformation of the embryo would result. In Daphnidac 



