230 



Wm. S. Marshall, 



is unstained; besides this there are many achromatin bodies in a 

 few of the larger of wbich tbe remains of tbe paired cbromosomes 

 may be seen. There are also a number of achromatin fibrils con- 

 nectiüg these parts. The changes from here we have spoken of in 

 another stage and will now only call attention to the nucleus of the 

 oldest oöcyte in this tubule. This (Fig. 49) shows a proportionally 

 smaller nucleolus and a great increase in the number of the achro- 

 matin bodies which do not as yet entirely fill the nucleus. 



KoRSCHELT (21) some time ago called especial attention to the 

 secretory activity of the nurse-cells in insect ovaries, and many 

 others have noted the same fact. This is shown so plainly in Platy- 

 phylax^ that we would call attention to it in this stage where it 

 shows as well as in any other. Before the group of oöcytes and 

 nurse cells have arranged themselves into Chambers (Fig. 43) this 

 activity has begun. The cytoplasm around the nuclei, especially 

 along those parts facing other nuclei, is darker and denser than that 

 found in the other part of the cell. This occurs on those sides of 

 the nurse-cell nuclei which face the oöcyte, and in that part of the 

 oöcyte which lies nearest the nurse-cell. These darkened masses 

 may fuse with one another or Strands may connect them. As yet 

 the regularity in outline of the nuclei has but slightly changed, if 

 at all. In older groups this is different (Fig. 46) for we find at least 

 one surface of each nucleus becoming very irregulär. This is due 

 to a sinking in of the nucleus at one point, and, where this occurs, 

 its surface is exceedingly irregulär. This in Platyphylax may go so 

 far as to nearly penetrate the nucleus or separate it into two parts. 

 A few cells may be found which at first appear to be binucleate, 

 but this appearance is only due to the partial Separation of the Single 

 nucleus. In older stages (Fig. 47) this activity is still noticed; the 

 oöcyte nucleus is also irregulär but not so markedly so as that of 

 the nurse-cells. 



Ovary G. This ovary is from an old pupa ; in each tubule there 

 are four or five Chambers and a terminal filament. The proximal, 

 oldest, Chambers show a great increase in size; they have broadened 

 so much that the last one is nearly round. The difference between 

 these and the others is not in size alone but also in the structure 

 of the oöcyte and its nucleus. 



The most distal of all the Chambers (Fig. 51 1) not only contains 

 a few cells in different stages of development, but, in its proximal 



