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Wm. S. Marshall. 



Bytisciis and Mantis. The threads staining darkly makes it imposs- 

 ible to always distinguish their beaded structure (Fig. 21). After 

 synapsis the threads become again distributed throughout the nuclens; 

 at first they are quite thiu and are beaded (Figs. 22 and 23). The 

 cells that come out of synapsis develop to either oöcyte or nurse- 

 cell (WoLTERECK [41]) but it is yet some little time before we can 

 distinguish between them. 



There now occurs a rather sudden change in nuclear structure 

 the transitions to which we have not been able to determine; this 

 is the change from the last stage (Fig. 23) to what we next find 

 (Fig. 24). In this latter we see that the threads have become very 

 much thicker and shorter, and that in each, two long, narrow chromo- 

 somes have appeared. These are thin, somewhat curved to follow 

 the shape of the thread, and they stain quite darkly. In diagonally 

 cut threads they naturally appear as two short rods. Conti*action of 

 the thread goes on, the chromosomes become shorter and thicker and 

 increase in distinctness (Figs. 25 and 26). The position of the cells 

 having such nuclei is shown (Fig. 15 g) and they are seen to lie 

 further towards the proximal end than any we have hitherto described. 



At least one quarter, the proximal, of this tubule, is occupied 

 with cells whose nuclei show, that the contraction of the threads and 

 chromosomes, is completed. Each piece of the former thread is now 

 nearly Square and contains a pair of short chromosomes (Fig. 27 . 

 The nucleolus is still present and remains unstained entirely or only 

 slightly tinged. 



Ovary C. This larval ovary shows very distinctly the grouping 

 of the oöcytes with their accompaning nurse-cells; no Chambers are 

 yet formed, nor do we find that the two or three oldest oöcytes, are 

 arranged behind each other in the tubule as in older stages. In 

 the section of the tubule [Fig. 28) we have drawn, we see the 

 proximal oöcyte lying in the middle, but other tubules from this 

 same ovary showed, at this region^ two lying side by side. The 

 proximal half of the tubule is occupied by groups of oöcytes and 

 nurse-cells, and in the distal half are cells which show the different, 

 earlier stages, of development. Of these latter we will here say 

 nothing the structure being similar to what has been described for 

 ovary B, and nearly the same, as we find in a slightly older stage, 

 ovary D, which we next take up. 



The ovary we now describe, C, shows so well the change and 



