SECRETIONS. 



83 



all, and thus ultimately communicating with the surface by 

 one or more apertures only, as in the amygdalae or tonsils, 

 they are called agglomerated follicles. At other times little 

 sacs, which form the essential structure of the glandular 

 bodies we now speak of, communicate with the exterior by an 

 elongated neck, so as to resemble a tube, terminated by an 

 ampulla, and there they may either remain isolated or agglo- 

 merated in bunches, by means of common excretory tubes, 

 which, in their turn, reunite successively, to terminate by a 

 single duct (Fig. 60). The secreting organs, which may be 

 called ampullary follicles, are met with in the simplest form 

 under the skin of certain fishes, and 

 seem also to form the odoriferous 

 glands found in the human integu- 

 ments. When grouped around a com- 

 mon branched secreting canal (Fig. 

 60), they form the greater number 

 of the composite glands, such as the 

 liver and salivary glands of mammals, 

 and are named by anatomists, Con- 

 glomerate Glands. 



156. The tubular- formed, se- 

 creting organs present also differences 

 analogous to those just described. 

 These tubes vary infinitely in size, 

 but are all closed at one extremity, 

 and open at the other for the escape 

 of the excreted matter; their varied 

 arrangements are seen in the glands 

 under the integuments in fishes, and 

 in the bilious vessels of some of the 

 lower animals; in the pancreatic 

 coaca surrounding the duodenum in 

 fishes ; in the gastric glands of several 

 birds ; finally, these same tubes (Fig. 

 61) may acquire an extreme length 

 without change in their calibre, clustered or heaped on them- 

 selves, to terminate in an excretory tube, but little ramified at 

 its origin, in such a way as to form a conglomerate gland, 



* A, vertical section of a kidney. a, cortical substance j 5, tubular sub- 

 stance; c, calyx and pelvis ; d, canal of the ureter. 



, intimate structure of this gland. a, terminal portion of the urinary 

 tubes ; b, medullary portion of these same tubes ; c, their termination in the 

 calvx. 



G2 



Fig. 61. Structure of 

 the Kidneys.* 



