No. 612] GENESIS OF ORGANIZATION OF INSECT EGG 717 



kinds of cytoplasm. The appearance of a definite polar- 

 ity might lead in some way to diffusion processes and the 

 circulation of secretions resulting in further specializa- 

 tions and localizations. One stage seems to initiate the 

 next stage in the series of processes that accompany the 

 visible changes in the growth and development of the egg, 

 and the character of these processes is of course due to 

 the specificity of the protoplasm. 



That the cytoplasm may exert a controlling influence 

 upon the chromatin has been demonstrated in several in- 

 stances. For example, we know that the chromatin- 

 diminution processes during the early cleavage of both 

 Ascaris and Miastor are controlled by the cytoplasm and 

 that in these animals the germ-cell nuclei retain the full 

 amount of chromatin because of the germ-cell cytoplasm 

 they chance to encounter. 



Probably the peculiar distribution of the chromosomes 

 at' certain stages in the life histories of certain aphids, 

 pliyloxerans, and llymenoptera is also controlled by the 

 {'yto])hism. In tlie aphid, Aphis snliceti, the first matura- 

 tion division is visibly dit'torontial l)oth as regards the 

 cln-oiiiosoiiies mid tlic (•\t()i)lasm.*" The mitochondria 

 congi-cgate at one end of the dividing spermatocyte; this 

 ])i'0(Mvss is accoiu])anied by a greater accumulation of 

 cytoplasm at this end so that cell division results in one 

 large cell containing all of the mitochondria and about 

 two thirds of the cytoplasm, and one functionless small 

 cell. The large cell also receives three chromosomes ; the 

 small cell only two. 



The peculiar maturation divisions in the males of the 

 honeybee" and hornet.*" during wliicli one ultimate sper- 

 mato.u-oiiinin .u'ix'o rix' to only one >i)('nn;itoziM)n instead 



