CH. XXXI.] 



SECRETING GLANDS 



497 



glands differ from each other only in secondary points of structure, 

 but all have the same essential character in consisting of rounded 

 groups of vesicles containing gland-cells, and opening by a common 

 central cavity into minute ducts, which ducts in the large glands 



Fia. 347. Diagram of types of secreting glands. A, Simple glands 



straight tube ; h, sac ; i, 

 c, Racemose, or saccular 



coiled tube. B, Multilociilar crypts ; k, of tubular form ; I, saccular. 



compound gland ; m, entire gland, showing branched duct and lobular structure ; n, a lobule, 



detached with o, branch of duct proceeding from it. r>, Compound tubular gland. (Sharpey.) 



converge and unite to form larger and larger tubes, and at length open 

 by one common trunk on a free surface. The larger racemose glands, 

 such as the salivary glands, are called compound racemose glands. 



2 I 



