186 Harry Lewis Wieman. 



staining nucleoli are present. The chromatin has passed from 

 the condition of beaded strands into a formless mass that takes 

 the acid stain. Finally an acid staining ground substance is 

 produced in which a number of basic staining nucleoli are em- 

 bedded. What relation these nucleoli bear to the nucleolus of 

 the resting stage I am at present unable to say. 



There are a number of facts that argue in favor of the nucleolus 

 of the resting stage being homologous in the two sexes. In the 

 first place in pre-reduction stages in both cases, a nucleolus is 

 present in the vegetative nucleus between mitotic divisions, but 

 it is entirely different in appearance from the one characteristic 

 of the growth period. It is often jagged in outline, and may be 

 single or multi-partite, while the bi-partite condition of the 

 nucleolus is strictly a feature of the resting stage. 



Secondly, the bi-partite nucleolus appears in both sexes at the 

 time of synizesis (Figs. 39 to 46). Wilson ('06, p. 22-23), speaking 

 of Anasa and other Hemiptera states: ''In the female no trace 

 of a chromosome nucleolus can be found in the contraction stage 

 of the synaptic period .... I can, therefore, only state 

 that no chromosome nucleolus is present in the contraction period 

 synapsis or in the early growth period, and even though it be 

 present in later stages, which I think very doubtful, a wide dif- 

 ference between the sexes would still exist in respect to the earlier 

 period." Evidently the conditions in Anasa and Leptinotarsa 

 are not the same, for the presence of the nucleolus in the latter 

 can be demonstrated without any difficulty. 



Thirdly, the behavior of this body in relation to the other 

 chromosomes in the early part of the growth period is the same in 

 both sexes (Figs. 39, 40, 41, 42 46, 47, and 48). 



The evidence all tends to show that this body is in some way 

 bound up with the processes connected with the early part of 

 the growth period. It persists in the ovocyte as long as the develop- 

 ment of the latter is parallel with that of the spermatocyte, but 

 as soon as the ovocyte begins to show signs of the highly special- 

 ized metabolism involved in its enormous growth, the nucleolus 

 can not be distinguished from a number of other bodies that make 

 their appearance at this time. 



