132 



THE FROG 



CHAI'. 



The 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 



IjTi cm ,^ f 



Fig. 40. — .\, part of a trans\ersc section uf tlic frog's stoni.icti ; II, one of the gastrie 

 glands in longitudinal section, highly inagiiilied ; C, tran>\erse section of a 

 gastric gland. 

 /'. V. blood-vessel ; c. cavity of gastric gland ; c . tii. circular muscles ; c. tii. iti, 

 circidar layer of muscidaris iriucosa; ; c/. epithcliunr ; i;. i^l. gastric glands ; 

 /. in. longitudinal muscles ; /. ;//. ;;/, longitudinal laj'cr of muscularis niticosa; ; 

 T!i. mouth of gastric gland ; mi. nucleus ; /;-. ]ieritoncum ; ,v. in. suhniucosa. 



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. 



