Germ Cells of Leptinotarsa Signaticollis. 169 



When about to divide, the nucleolus appears as an abnormally 

 large basic-staining body surrounded by a perfectly clear area that 

 serves to intensify the vividness of the dye. Fig. 68 shows the 

 separation of the daughter halves during which process the clear 

 area takes the shape of an hour-glass. The constriction then ex- 

 tends to the nucleus itself (Fig. 69), and eventually to the entire 

 cell. 



The amitotic period for any given cells is not of long duration, 

 not more than perhaps several cell generations; although this 

 could not be determined very precisely. It begins in the larval 

 period at about the time of cyst formation, with the early develop- 

 ment of which it is concerned. At any rate, in the earliest stages 

 at which the cysts can be recognized, they are filled with cells 

 undergoing amitosis. A little later these same cysts are filled with 

 mitotic spindles, after which no evidence of direct division is to be 

 found. It is thus seen that the early stages in the building of 

 cysts in the testis are practically the same as those described for 

 the formation of the analogous structures among the nurse cells 

 of the ovary. 



While the appearance of the amitotic figure here is entirely 

 different from that found in the nurse cells of the ovary, there 

 are several points of resemblance. In the first place, the nuclear 

 membrane remains intact in both cases. Secondly, the chromatic 

 part of the cell is surrounded by a clear region; extra-nuclear in 

 the case of the nurse cells, and intra-nuclear in the cas'e of the pri- 

 mordial germ cells of both ovary and testis. Thirdly, in both, the 

 process is connected with cyst formation, except in the primordial 

 germ cells of the ovary. 



Perhaps the most striking differences are that in the nurse cells 

 direct division continues indefinitely, resulting in certain chemical 

 changes in nucleus and cytoplasm, and that it is not followed by 

 mitosis; while in the germ cells it is, of relatively short duration 

 and is followed by mitosis: the cells developing into functional germ 

 cells. Evidently the process does not have the same significance 



the two cases. 



The fact that the amitotic divisions occur in the germ cells of 

 the ovary for only a very brief period makes it somewhat difficult 



