2G 



SPECIAL HISTOLOGY. 



simplest glands (fig. 178), only a few (4 — 8) exist, are in their 

 circumference generally elongated, pyriform, or rounded, not 



rarely, flattened,0-5 — 0-72'" 

 long, 0-2 — 0-48'" broad, 

 and are each seated upon a 

 branch 003 — 005'" thick, 

 of the excretory duct, which 

 measures 0*12 — 03"', or 

 even 05'", (in the glands of 

 the root of the tongue). 

 They consist of a number 

 of coiled canals present- 

 ing numerous simple or 

 compound, vesicular diver- 

 ticula (fig. 179), and ap- 

 pear to be the immediate 

 continuations of the excre- 

 tory ducts of the lobes, which, 

 as soon as they have entered 

 the latter, usually without 

 diminishing in diameter, break up successively into a certain 

 number of them. What have been called the glandular vesi- 



Fig. 179. 



cles or acini, are nothing more than the dilatations and termi- 

 nations of these canals, or ultimate branches of the excretory 

 ducts. Examined superficially, and under low magnifying 



Fig. 178. Racemose raucous gland from the floor of the oral cavity: a, investment 

 of connective tissue ; b, excretory duct ; c, glandular vesicles ; d, ducts of the lohes ; 

 from Man, x 50. 



Fig. 179. Diagram of two ducts of a lohe of a mucous gland : a, excretory duct of 

 the lobe; b, secondary branch; c, the glandular vesicles upon it in situ; d, the same 

 separated and the duct unfolded. 



