2,56 STEUCTUKE OF GLANDS. 



the pancreas. The lung of the mammal, with its terminal 

 vesicles attached to the minute ramifications of the bronchi, 

 may serve as a prototype of this form of gland, which is made 

 up of repetitions of the same fundamental structure, as we 

 have seen in the preceding paragraph to be the case with 

 regard to the Harderian gland. 3. Glands with a tubular 

 structure ; the secreting canals are here extremely slender, of 

 great length, convoluted, blind at the ends, not ramified, or 

 only once or twice divided, not sensibly or but very slightly 

 enlarged at the extremities, sometimes anastomosing by re- 

 current loops, or connected by cross branches, and from the 

 tenth of a line to half a line in thickness ; to this category 

 belong the kidneys and the testicles especially. The Cowper's 

 gland of the hedge-hog (fig. 256) may serve as a prototype 

 of the form of which that of the organs just mentioned may 

 be viewed as an extension. 4. Acmous (/lands. The excretory 

 duct here ramified through the substance of the gland, divides at 

 length into extremely minute branches ; all the branches and 

 twigs are beset with compact lobules, consisting of very small, 

 firm, angular cells, which effect the secretion. To this division 

 belongs the liver of vertebrate animals generally. 



[422. Compound follicles or glands of the first descrip- 

 tion, are progressive or more complex forms of the rounded or 

 elongated inversion, which we have seen constituting the 

 simple follicle of the mucous membrane and of the skin (419); 

 no precise line of demarcation can, in fact, be drawn between 

 them and the simple follicle, or the sudoriparous or cerummous 

 gland. The large glands of the stomach and intestines may 

 serve as types of this kind of gland (fig. 182), or the numerous 

 glands which are in connection with the skin. All these glands 

 consist of ramifications of the excretory ducts, which swell out 

 into single saccules, that do not combine into true racemes or 

 lobes. The glands which areconnected with the hairs (fig. 248 

 c, #, a, and 25 1, ad) are small follicles, with rough external sur- 

 faces, and internally presenting the appearance of projecting pa- 

 rietal cells. To this division also belong the associated un- 

 branched saccules arranged along the excretory duct like the 

 grains of an ear of barley, which compose the Meibomian 

 glands.* Among animals a multitude of variously formed 



* Figured by Miiller De Gland, structura, Tab. v. figs. 1 and 2. 



