142 Harry Lewis Wieman. 



without the slightest doubt, between germ and epithelial cells; 

 while the nurse cells have not yet been differentiated. Further- 

 more, the germ cells are practically unaltered in appearance from 

 early embryonic stages. Figure 1, represents a longitudinal 

 section of an egg tube characteristic of the larval condition, in 

 which one of the striking features is the direct continuity between 

 the cells of the terminal thread (tt) and those of the terminal 

 chamber. In the region of the terminal chamber two kinds of 

 cells can be readily made out, the large germ cells (g.c.) with deeply 

 staining cytoplasm and with nuclei showing an irregular chromatin 

 reticulum, and the small pale epithelial cells (ep.c.) continuing 

 outward into the terminal thread. The ovariole stalk is composed 

 of +all columnar cells (o.st.c). The peritoneal sheath is in the 

 process of formation, and is represented by the large epithelial 

 cells (p.sh.) which are flattened against the sides of the tube. 

 Beneath this outer sheath lies the tunica propria (t.pr.) bounding 

 the terminal chamber and thread. The ovarioles are united by 

 their terminal threads coming together on either side into a single 

 bundle which is inserted into the dorsal wall of the body cavity. 

 (Fig. W, A). 



The epithelial cells scattered between the germ cells are what 

 the older authors designated as the small nuclei surrounding the 

 ovocyte, to which they supply nutrition. In the figures of these 

 authors, these cells are never shown with cell boundaries, but 

 always as nuclei lying in a homogeneous matrix. At best it is 

 not easy to make out cell boundaries, since the cytoplasm shows 

 such a weak affinity for the stain, but a careful study of many sec- 

 tions at different stages has convinced me that cell walls are pres- 

 ent and that each nucleus belongs to a single cell, except under 

 certain conditions as noted below. At a.c. is a large cell which I 

 have designated the apical cell, the significance of which I have 

 been unable to determine. It is also seen in later stages (Figs. 2,3). 



The fact that the epithelial cells show such a slight affinity 

 for the stain, seems rather strange in view of what appears to be 

 their function; namely, to supply nourishment to the germ cells. 

 Ordinarily, cells having a secretory function show in their cyto- 

 plasm more or less granular masses which stain deeply. Are they 



