390 Ralph S. Lillie 



of typically regular and equal cleavage on the other. The irregu- 

 larities are extremely various, and it is difficult to assign any defi- 

 nite conditions to the production of any particular kind. They 

 seem largely due to changes occurring in the cytoplasm independ- 

 ently of the nucleus; in other words, there is frequently a lack of 

 correlation between nuclear and cytoplasmic activities in the 

 warmed eggs; certain processes are initiated in both, sometimes 

 leading to nuclear division independently of cytoplasmic division, 

 at other times to the apparentlyindependent assumption of irregular 

 forms on the part of the cytoplasm, with the production of irregular 

 pseudopodia, usually followed by subdivision of the cytoplasm into 

 unequal cleavage cells or still smaller enucleate fragments. Such 

 fragmentation is very typical of eggs that have been warmed 

 for too prolonged periods; the formation of small bead-like pro- 

 tuberances which then separate from the rest of the cell-body is an 

 especially frequent phenomenon. These conditions as a rule 

 reach their height about three or four hours after warming, at a 

 time when the first cleavages usually begin to appear in regularly 

 dividing eggs. 



The production of protoplasmic processes af times shows remark- 

 able peculiarities, particularly in eggs derived from animals late 

 in the season or otherwise unfavorable. The proportion of irregu- 

 lar form-changes is also greater in eggs warmed after maturation 

 is complete (p. 402). A slightly prolonged warming often leads 

 to the production of numerous long slender close-set pseudo- 

 podia of clear protoplasm, of a uniform length sometimes equal 

 to that of the egg-radius, imparting a prickly or radiating appear- 

 ance to the entire structure; irregular fusions may take place between 

 these processes as in the pseudopodia of Foraminifera.^^ These 

 cytoplasmic activities seem to have little directly to do with nuclear 

 influence; separated enucleate portions of protoplasm may also 

 undergo irregular form-change or subdivide still further. Other 

 instances of specific change of form in enucleate portions of eggs 

 have been described by several observers. It seems clear that the 



17 Such conditions seem frequent in abnormally developing parthenogenetic eggs; compare especially 

 the accounts of F. R. Lillie for Chastopterus, loc. cit., p. 487; also of Lefevre for Thalassema, he. cit.y 

 p. 109. 



