DIGESTIVE SECRETIONS AND THEIR CONTROL 433 



Fio. 137. Forms of glands. A, a simple secreting surface; a, its epithelium; 

 6, basement membrane; c, capillaries; B, a simple tubular gland; C, a secrvtmn 

 surface increased by protrusions; E, a simple nirrmosr glimd ; 1> and <;. r>m- 

 pound tubular glands; /'. a compound racemose gland. In all hut .1, li. and C 

 the capillaries are omitted for the sake of clearness. //, half of a highly developed 

 racemose gland; c, its main duct. 



