132 



THE FROG 



CHAP. 



Tlie cells of the gastric glands have the power of forming, 

 out of the materials supplied to them by the blood, the 

 gastric juice, by which, as we have seen (p. 74), proteids 

 are digested. Thus, while the raw material supplied to both 

 cutaneous and gastric glands is the same, the manufactured 

 article is entirely different in the two cases. Each kind of 



Fig. 40. — A, part of a transverse section of the frog's stomach ; B, one of the gastric 

 glands in longitudinal section, highly magnified ; C, transverse section of a 

 gastric gland. 

 b,v. blood-vessel; c. cavity of gastric gland; cm. circular muscles; c.vi.ni. 

 circular layer of muscularis mucosae ; ep. epithelium ; g. gl. gastric glands ; 

 I. in, longitudinal muscles ; /. in. in., longitudmal layer of muscularis mucosae ; 

 in. mouth of gastric gland ; »». nucleus ; jir. peritoneum ; s. in. submucosa. 



gland-cell has the faculty of picking and choosing, the 

 material supplied being worked up in the one case into the 

 cutaneous secretion, in the other into gastric juice. 



