THE GERM-CELLS OF CICADA (TIBICEN) SEPTEMDECIM. 415 



plication stages. Wilcox ('95) has described giant spermatids 

 and spermatozoa in Cicada tibicen; he also finds that they are 

 derived from abnormal spermatogonia in which there has been 

 a failure of the division of the cell-body, and that their develop- 

 ment insofar as the spermatozoan is concerned follows a normal 

 course with the production of typical spermatozoa which merely 

 differ from the normal ones by their large size. It seems difficult 

 to ascertain the significance of these giant cells or whether there 

 is any possibility that they play a part in the fertilization of the 



egg- 



3. Growth Stages and Synapsis in Oocytes. 



While it has not been possible to study the process of synapsis 

 in the spermatocytes due to the absence of the proper stages in 

 my material, in the oocytes I have been able to follow the various 

 growth stages in some detail. 



The young oocytes in varying stages of growth are found at the 

 base of the nurse chamber or "Keimlager" (Fig. 34). They are 

 always distinguishable from the nurse-cells by their definite cell 

 outline, by the thread-like appearance of the chromatin as com- 

 pared to the granular nuclei of the nurse cells, and by the presence 

 of a definite mitochondria! zone. Only occasionally could oogon- 

 ial divisions be found in the ovaries of the youngest pupae, and 

 hence I have been unable to trace the chromosomes from the 

 last oogonial division into the early growth stages. The very 

 early growth stages (leptotene, etc.) are not found in the material 

 collected after the latter part of April but in the material col- 

 lected earlier, there is an abundance of oocytes in the pre- 

 synaptic stages. 



Figure 35 is that of the nucleus of a young oocyte corresponding 

 to von Winiwarter's "protobroque" nucleus. The chromatin is 

 in the form of a network with the nodal points of the net staining 

 somewhat more deeply than the rest of the reticulum. On closer 

 analysis of this nucleus it is seen that the net-like appearance 

 of the chromatin is due simply to the optical effect of numerous 

 delicate chromatic threads crossing each other in all directions. 

 In the later stages the individual threads become more evident 

 and this stage (Figs. 36, 74) no doubt corresponds to von Wini- 

 warter's "deutobroque" nucleus. Gradually these threads as- 



