THE GERM-CELLS OF CICADA (TIBICEN) SEPTEMDECIM. 409 



been described, especially in the follicles surrounding mature 

 oocytes; but I have failed to find any strong evidence for the 

 occurrence of this method of nuclear division. The only indica- 

 tion that amitotic division may take place is found in the follicles 

 surrounding the old oocytes. Here the cells are usually bi- 

 nucleate and appear to be the end stages of amitotic divisions. 

 However, I have found many karyokinetic figures among such 

 cells and it seems reasonable to suppose that the binucleate 

 follicle-cells arise through the failure of the division of the cell 

 body following mitotic division of the nucleus. 



All metaphase plates of dividing follicle-cells show 20 chromo- 

 somes (Figs. 3, 4, 5, 6, Text-fig. 2), and it is possible in all of 

 these to recognize the chromosome pairs AA, BB, and CC as in 

 the spermatogonial plates, by their size relations. Figure 12 

 is that of the late telophase of a dividing follicle cell in which 



c 9 



/ET* 



i:.* 



TEXT-FIG. 2. Two metaphase plates from ovarian follicle-cells showing the 

 A A, BB, CC pairs of chromosomes; note that the A A pair lies in the center of 

 the group. 



one of the macrochromosomes (A) can be recognized in the 

 daughter cells. It will also be seen that there is present a 

 precocious longitudinal split of the chromosomes in preparation 

 for the next cell-division. 



In the follicle-cells surrounding the older oocytes, the chromo- 

 somes do not have the thick compact appearance found in the 

 younger follicle-cells. The chromosomes- are usually thinner, 

 poor in chromatin content, and the respective chromosomes 

 appear somewhat longer, often showing an equational split 

 (Figs. 10, n). I am unable to account for this difference in 

 appearance of the chromosomes (compare Figs. 7, 10, n). In 



