The cellular elements of the Ovary of Platyphylax designatus Walk. 219 



also shows a more advanced stage, represented however by few cells 

 and these at the proximal end. In these (Fig. 7) the former large 

 chromatin grannles have entirely disappeared and the Strands have 

 become quite regulär. In these nuclei are seen a number of dark 

 and of light granulös; the former are the ends of the Strands, seen 

 in real or optical section, the latter represent the beginning of a 

 beaded structure which becomes more noticeable in older stages. 



The second, more advanced, tubule from ovary A (Fig. 8) shows, 

 even under a low power, quite a difference from the one we have 

 described. At the distal end, and along a part of the margin, are 

 a number of cells with nuclei very similar in structure to those we 

 found present in the younger tubule. We find some which are similar 

 to those we have designated as the youngest, undifferentiated, stage; 

 others are also present with large prominent chromatin granulös 

 (Fig. 9 b) and some in which these have begun to disappear and the 

 chromatin Strands to become more distinct. As development goes 

 on the chromatin granulös decrease in size and regularity of position 

 and the Strands, which before this were prominent, begin to show a 

 beaded appearance (Fig. 9 c). In larvae of Bomhyx GrÜnberg (12) 

 observed that the oogonia lying nearest the oviduct, changed the 

 original arrangement of their chromatin and form a spireme. After 

 the disappearance of the chromatin granulös, beaded Strands are all 

 that we notice, except the nucleolus, within the nucleus (Figs. 11, 

 12 and 13). Along the margin some cells show, by the structure of 

 their nuclei, that they are not so far advanced. 



In all the tubules of this ovary there are found a few cells 

 which are larger than any of the otliers (Fig. 14), These apparently 

 pass through the same stages as the others and can be found in 

 any of those we have so far described. At first it seemed possible 

 that these were the oöcytes, which, in the later stages, will be seen 

 to be larger than the nurse-cells, although their nuclei show but a 

 slight, if any, difference in size. This explanation seemed very good 

 but when we came to study the older stages we failed to find a few 

 cells larger than the others. It seems more likely that there is a 

 considerable dilference in the size of the cells, and that the few 

 largest are, from their size, more noticeable than the others. 



We notice, in this youngest larva, that there are many different 

 nuclear structures but that they are all very similar to some one of the 

 several we have described. The first differentiation of the cells has 

 here taken place, and we find that they all come under one of two 



