1.88 



Wm. S. Marshall, 



Tliis entire ovary showed very few dividing cells ; one or two 

 scattered mitotic figures were seen in the region where the distal 

 changes into the median part of the tubule, and small groups of them, 

 in the proximal part of this latter portion. Henking (13) found in 

 the larva of Pyrrhocoris, that the mitotic figures were present in two 

 regions, in the upper part of the »Keimfach«, and just under it. 



We see that in this stage it is hard to determine the oöcytes 

 with as much certainty as the primitive nurse cells, and we fail to 

 find, at any place in the ovary, the large cells which, from their size 

 and structure, are, in later stages, so easily distinguished as oöcytes. 

 We find that oöcytes are differentiated (Fig. 15), but that their develop- 

 ment has not gone so far as that of some of the primitive nurse cells, 

 many of which have at least gone through one division. Earlier, 

 in ovary B, we saw a differentiation of cells with small, ovoid 

 nuclei, to those with larger and rounder ones. Some of the cells 

 with the small ovoid nuclei do not change, and can, in later stages 

 (as epithelial cells), be found in both the distal and the median portions 

 of the tubule; in the latter region division in these cells does not 

 cease, and they increase in number long after division in the nurse 

 cells has stopped. The cells with oval nuclei, which are found here 

 in the distal part of the tubule, either remain as they are and may 

 become epithelial cells or differentiate into oöcytes or primitive nurse 

 cells. 



We have found that the ovary from a larva which has enclosed 

 itself in the cell of its nest is further developed than one from a 

 free larva. This its naturally what would be expected and is in 

 general true but we may find exceptions. Some free larva are found 

 in which the ovary is further developed than is some of the en- 

 closed ones. From this it can be seen that a study of the ovary 

 alone, would not be a sure criterion as to whether it had been 

 taken from an old, free larva, or from on which had just enclosed 

 itself for pupation. 



Ovary D. Passing to a wasp which has commenced to pupate 

 we find that a general view of an ovarian tubule is similar to what 

 we found in the last stage. At that point in the tubule where the 

 widening is most marked (Fig. 18 T) we find a change taking place 

 in the structure of the nuclei and in the form and size of the cells; 

 at this place, if any, we find a zone ot differentiation (Paulcke), and 

 of the first differentiation, which takes place. Korschelt (18) found 



