Testis of Leptinotarsa Signaticollis. 489 



make the comparison complete, corresponds to the terminal 

 chamber of the ovariole. 



It will be noted that some of the germ cells at the lower (prox- 

 imal) end of the lobe (B) are grouped into cysts (c) while elsewhere 

 the cells are free. As has already been pointed out (Wieman, 

 '10), a careful study of these stages led me to believe that each 

 cyst arose from a single mother cell by an amitotic method of cell 

 division, similar to the manner in which cyst formation takes 

 place in the nurse cells of the ovary. 



In figs. 3, 5, 8, etc., abundant evidence of amitosis can be seen. 

 The division begins with the constriction of a large basic staining 

 nucleolus into two parts, after which the nucleus undergoes a sim- 

 ilar division. Division of the cytoplasm does not take place im- 

 mediately and as a result bi-nucleated cells are frequently seen. 

 Actual division of the cytoplasm is very difficult to demonstrate, 

 but that it must occur is evident from the fact that the spermato- 

 cytes that result from these cells are cells with single nuclei. 



After the cysts are definitely formed amitotic figures disappear 

 and all subsequent divisions are mitotic. As cyst formation be- 

 gins in the lower (proximal) end of the lobe, amitosis disappears 

 first in this region; while in the other parts it continues as long as 

 the spermatogonia are not grouped into cysts. As a result, in 

 the fully developed organ, in the region of the cap in the distal 

 end of the testis amitotic figures abound. 



In the larval stage shown in fig. 3 there is no evidence of degen- 

 eration. The first indication of such a process is shown in fig. 

 4, B, which is from a larva about two days older, and consists in 

 an accumulation of epithelial cells at a point removed from the 

 distal end of the lobe a distance of one-third the length of the en- 

 tire lobe. This stage is shown diagrammatically in fig. 2, B. 

 The cells are irregular and ragged in outline, and this, together 

 with the fact that there is a considerable amount of inter-cellular 

 substance, suggests a process of liquefaction or secretion. The 

 germ cells are readily distinguished by their large rounded nuclei 

 and deeply staining cytoplasm so that there can be no doubt about 

 which cells take part in the process. 



