THE ORIGIN AND DEVELOPMENT OF GASTRIC GLANDS. 9 1 



d} and, in this way, the excretory ducts are formed. The fundus 

 of the gland, composed of deeply staining granular cells, remains 

 near the basement membrane. In a later stage the fundus also 

 elongates. 



To recapitulate briefly : the fundus of the gland is formed from 

 clear round cells lying at the base of the epithelium ; the neck is 

 formed from the epithelial cells which take part in uniting these 

 to the surface epithelium ; the excretory ducts are formed sec- 



FlG. 31. Transaction through the fundus of the stomach of a pig 16.5 cm. long. 

 Same as in Fig. 32. Formalin. The mucosa is pushed out even straighter than in 

 the preceding figure, so that the gland cells open almost on the surface of the stomach. 



ondarily--by outgrowths of the single layer of epithelial cells, 

 covering the processes of the primary outgrowths of the meso- 

 derm, and also by a continued insinking of the surface epi- 

 thelium. 



It is not surprising that to these solid epithelial and mesoder- 

 mic outgrowths, or projections, should have been ascribed the 

 origin of the glands by Kolliker ('52), Laskowsky ('68), Brand 

 ('78), Negrini ('86) and Salvioli ('90). For, in the pig at least, 

 the round clear cells are very small, while these so-called " gland 

 processes " are so marked and present so striking an appearance 

 that it is little wonder that they should have attracted the most 

 attention, and in them should have been sought the sole explana- 

 tion of the glandular origin. In 1880 Toldt described, for the 

 cat, solid epithelial masses " Ersatzzellen," as occurring at the 

 base of the epithelium. These, he said, became arranged in a 

 special form, degenerated in the center to form a vesicle or min- 

 iature gland. The vesicles then lengthened and divided to form 



