Conti', towards tlie Embiyology and Anatomy of Polistes pallipes. 197 



disintegrating- cells are seen within the tubule ; more here tliau at 

 earlier stages. 



Just as we found, that, when larvae first enclosed themselves 

 within tlie cells of their nest, they did not always show an equal 

 development, so we now find that upon issinng from it, the ovaries 

 are not all the same. We have selected a specimen which will 

 represent the average development that the ovaries have reached in 

 wasps which have been but a few hours out of the nest. 



The distal portion of the tubule shows the changes we have 

 already recorded for both oöcytes and nurse cells. We find a place 

 in which the cells are as yet undifferentiated and, proximal to this 

 region, the nuclei undergo the same changes we have already noticed. 

 A certain zone contains all the synapsis nuclei, which are however 

 not abundant; some sections show none at all, and never more than 

 two or three. In taking up the history of the different cells it will 

 be best to treat of each kind separately, and to omit several stages 

 we have already described. 



The epithelial cells and their nuclei undergo by far the least 

 change of all; here and there along the margin of the tubule, we 

 find nuclei similar in structure to those we have already noticed as 

 belonging to epithelial cells. When the Chambers are formed, we 

 find, in the portion occupied by the oöcyte, that the epithelial cells 

 form in part a layer around it. In the region occupied by the nurse- 

 cells we find the same nuclei on its margin ; they are here also 

 scattered among the nurse-cells (Fig. 79) especially in the median 

 part of the Chamber (Geoss [10]). The boundaries of these cells is 

 hard to distinguish, the nucleus is ovoid, but much smaller than that 

 of the nurse cells. In each, one or two, small, irregulär, achromatin 

 masses are found (Fig. 58), and a number of quite distinct achromatin 

 Strands, one or two of which can generally be traced across the 

 nucleus from side to side. A few chromatin granulös are present, 

 mostly peripheral in position. As soon as the Chambers become 

 definitely formed the epithelial cells begin to build a continuous layer 

 around the oöcyte, enclosing it at all points, except centrally where 

 it lies next to its nurse cells, where, as already noticed by many 

 others, an opening remains. At the two ends of the oöcyte the 

 epithelial cells assume a regulär columnar form and its margin has 

 here a serrated appearance, each indentation as long as the follicle 

 cell is Wide (Fig. 59). The nucleus of each of these epithelial cells 

 is similar to those within the nurse Chambers. We find a number 



