The celliilar elements of the Ovaiy of Platyphylax designatiis Walk. 231 



part, are to be found an oöcyte and its accompanying nurse-cells. 

 The cells in the distal part do not show a very great Variation in 

 structure, and it would be hard, from so old an ovary, to find all 

 the changes in their development. We find both ovoid and spherical 

 nuclei in which there are a number of large chromatin granules, the 

 majority of the cells here being in this stage (Figs. 53 h and 54). 

 A few cells are also present in which the Strands are becoming very 

 prominent (Fig. 53 c). From this stage we pass directly to the group 

 of cells in the proximal part of the tubule, without finding spireme- 

 thread or synapsis stages. It is not likely that the oöcyte in this 

 or even the following Chamber ever develops. An examination of 

 the ovary of a mature Platyphylax seldom shows more than three 

 Chambers containing mature eggs. This means of course the number 

 in an ovarian tubule, not in the entire ovary. As the eggs are all 

 laid soon after the mature insect emerges, and, as its life :'s very short, 

 it is hardly possible that eggs which are not entirely developed before 

 the mature insect emerges, will ever do so. Platyphylax is similar 

 in this respect to the Lepidoptera; the same has been observed by 

 Gross (10) in other forms of insects. 



The oöcyte which lies at the base of this youngest, most distal, 

 Chamber, has a somewhat flattened nucleus. It contains an achromatin 

 nucleolus (Fig. 55) and a number of paired chromosomes similar to 

 other nuclei we have described. The nurse-cell nuclei are the same 

 as those we have found in the youngest stages. In the entire 

 Chamber there were but a few epithelial nuclei some showing a 

 regulär arrangement around the oöcyte. 



Nothing new is seen in the next Chambers. In each the oöcyte 

 nucleus contains a number of paired chromosomes although, in the 

 older one, these are beginning to break up. The nurse-cells of both 

 Chambers show a normal structure, the nucleus of each containing 

 a few nucleoli and many of the small granules we have already 

 noted in other stages. 



The two oldest Chambers show considerable differences from 

 anything we have hitherto found, and they are in a much older stage. 

 This is not true of the nurse-cells which, except in their larger size, 

 are quite similar to the oldest ones we found in the last stage (Fig. 47). 



Both of the oldest Chambers are similar in structure. All of 

 the epithelial cells that can be seen around the nurse-cells are a 

 few nuclei, which are found along the margin of the tubule. Around 

 the oöcyte they are somewhat flattened and retatively smaller than 



