132 



THE FROG 



CHAP. 



forming, out of the materials supplied to them by the 

 blood, the gastric juice, by which, as we have learnt 

 (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 



FIG. 40. A, part of a transverse section of the Frog's stomach ( x about 50) ; B, one 

 of the gastric glands in longitudinal section ( x about 300) ; C, transverse section 

 of a gastric gland. 



b. v. blood-vessel; c. cavity of gastric gland ; r. m. circular muscles; c. m. m. 

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

 /. m. longitudinal muscles ; I. m. m. longitudinal layer of muscularis mucosae ; 

 m. mouth of gastric gland ; nu. nucleus ; pr. peritoneum ; s. m. mucous 

 membrane : the submucosa is external to the muscularis mucosae. 



in the two cases. Each kind of 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. 



The mucous membrane of the stomach is traversed 



