Contributions to the Anatomy and Histology of Thalassema neptuni Gaertner. 549 



and the consequent contortion and distortion of the columnar epithelial 

 cells, gives the epithelium an almost stratified appearance (Fig. 17). 

 As a basis we have the cylindrical cells, apparently the sup- 

 porting element, comparable as such to the "Fadenzellen" of the 

 epidermis (Fig. 17 ep.c). They are thread-like basally, broadening 

 out distally to form a pavement-like epithelial surface. In lon- 

 gitudinal or transverse sections owing to the height of the epi- 

 thelium these cells are rarely to be followed in their complete 

 length, they more frequently appear to form a network surrounding 

 the gland cells. Distally they show a cuticular margin, their proto- 

 plasm is highly granular, their nuclei are elongate, stain deeply and 

 contain a number of large very deeply staining granules. The level 

 of the nuclei varies somewhat; as a rule they are fairly central 

 (Fig. 17 ep.n). 



The gland cells are by no means all alike, yet, I believe that, as I 

 have found all possible gradations from the "Basalzellen" ^) to the 

 most highly modified glands, they may all be stages in the development 

 of the same glands. Similar glands, although less complicated, occurred 

 in the oesophagus (Fig. 15) and helped me considerably in my inter- 

 pretation of the state of aftairs in the crop. 



The simplest type of such cells, the basal cells (Fig. 17 gl.c), 

 which I take to be the first stages in the development of the more highly 

 specialized glands, are generally basal in position, and their contents 

 are fairly homogeneous, staining in haematoxylin and Bismarck brown 

 less deeply than the columnar cells. Their nuclei {gl.n) are round, 

 do not stain deeply, but have a few deeply staining refractive granules. 

 The next stage {gl. c') is the appearance of a deeply staining secretion 

 in the distal end, which is often seen to open out into the cavity of 

 the alimentary canal. The amount of this black staining secretion 

 increases relatively as the cell becomes more mature {gl. c"), so as 

 finally to be in excess of the lightly staining plasma. This secretion 

 always shows a tendency to occupy the distal part (neck) of the 

 gland; these necks are often much attenuated. 



When the secretion has reached a high state of elaboration the 

 nucleus is seen to become smaller and apparently effete {gl.c"., gl.n') 

 and we find stages in which the contents are almost completely 

 discharged, only a small quantity remaining in a little flask-shaped 



1) see note p. 547. 



