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Wm. S. Marshall 



or two nucleoli are^ as in tlie younger nuclei, present, and in many of 

 the cells a yolk-nucleus is seen. In the proximal third of the middle 

 portion of the tubule we find, besides tliese last nuclei, others which 

 are in general appearance lighter, due to their having bnt a few 

 chromatin granules ; these we will describe and fignre from the next 

 stage. 



In this median portion of the tubule, especially in the proximal 

 half, we find a few nuclei different from the others we have 

 described in this ovary. These (Fig. 25), are large and irregulär in 

 shape, each has one or two large achromatin nuclei and small, very 

 distinct chromatin granules. A comparison of these with some of 

 the nuclei (Fig. 15) we found in the last stage will show a siniilarity 

 between the two and we undoubtedly have here the young oöcytes. 

 The structure of their nucleus at once separates them from the 

 primitive nurse-cells, but does not, at this early stage, show any of 

 the peculiar structures we later find so characteristic for the oöcyte. 



In the distal portion of the tubule but few dividing nuclei are 

 found and these do not occur in groups. In the median portion we 

 notice quite a number, especially in the middle or proximal part, 

 and find that they nearly all occur singly; in only one place was a 

 group of dividing cells seen and here they failed to show any 

 connection with each other. 



Ovary E. In a slightly older stage, while the ovarian tubules 

 show but little change from what we found in ovary D, we find the 

 nuclei further advanced. That part of the tubule which becomes the 

 oviduct (Fig. 26 odt) shows in part, a lumen. Throughout the entire 

 distal portion of the tubule (Fig. 26 part f) no changes have occurred, 

 its terminal part contains cells similar to those in the last stage and 

 which, here and there, extend entirely across the tubule. Further 

 down (Fig. 26 point 27) we notice that the nuclei of the cells are 

 similar to what we found in those taken from nearly the same 

 Position in ovary D; they are oval in form, with one or two, seldom 

 more, achromatin nucleoli, and a number of chromatin granules lying 

 in Strands which are quite distinct (Fig. 27). We find that, in the 

 distal portion of the tubule, the cytoplasm of the cells is not so compact 

 and dark as in cells from the median part. A few dividing cells 

 can be found in this distal portion, but they are scattered, and do 

 not all occur in any one region. 



The first distinct changes in nuclear structure are found here in 



