THE DUCTLESS GLANDS 



307 



eft. c. 



the glandular lobe of a cat's hypophysis. 

 c.c., chief cells; ch.c., chromophilic cells. 

 X8 75 . 



appears, and the tissue (Fig. 276) appears as a series of compact cords 

 of cells, among which pass many small blood vessels. This blood sup- 

 ply is not as abundant as it was in 

 the infundibular gland. 



A principal point to be observed 

 is that the cells are of two kinds, a 

 larger cell filled with a purely granu- 

 lar secretion, and a smaller cell that 

 does not stain in the same way and 

 is not filled with a secretion. These 

 may be two varieties of cells, or they 

 may be different physiological stages 

 of the same kind of gland cell. They 

 have been designated by the manner 

 in which they take up different ani- 



lin dyes as the chief cells and the FlG . 276 ._ Sma ii portion of tissue from 

 chromophilic cells. 



The palatine tonsils of an oppos- 

 sum, Didelphys, may be considered 

 here because of their origin, and also because they act, in a manner at 

 least, as ductless glands, although the imaginations from which they are 

 derived remain in open communication with the digestive lumen. Each 

 tonsil consists of a slightly raised area from which several crypts have 

 been formed by invagination. The stratified epithelium of the oral 

 cavity is continuous through these amplifications, but becomes thinner 

 at the bottom of each infolding. 



Beneath the epithelium is a thick, mesoderinal layer composed of 

 connective tissue infiltrated by lymphatic cells. Lymph nodules or 

 germinal centers are found through this mass at regular intervals, and 

 they are typical of lymphatic tissue in every way. As a rule, the lym- 

 phatic tissue is but one nodule thick. In many forms, however, it is 

 apparently thicker, owing to a greater involution of the epithelium. 



It is in the relation of this lymphatic tissue to the invaginated epithe- 

 lium that the tonsil possesses a specific character which allows one to 

 speak of it as a "gland." Some of the amoeboid lymph cells are con- 

 stantly forcing their way distally between the epithelial celts, 'and find- 

 ing their way out of the body into the digestive tube. They are nu- 

 merous in the saliva and mucus, and possibly act as scavengers and 

 destroyers of bacteria. They pass through the epithelium in greater 

 numbers during certain conditions of the body, and they also come 

 through certain parts more than they do through others. 



The illustration (Fig. 277, A and B) shows two small portions of 

 the epithelium which lines one of the several tonsilar crypts of the opos- 



