184 ANIMAL PHYSIOLOGY. [LESSON 52. 



ly long and narrow ; nothing can exceed, however, the beautiful ar- 

 rangement of their capillary plexuses (Fig. 290). The small intes- 

 tine of the Cat shows this very nicely, but in the Lion (Fig. 291) it 

 is still better shown, as the capillaries in the Cat are of extreme 

 tenuity ; but in the latter the vessels and the villi both attain their 

 maximum development, so far as is consistent with this class. 



799. The intestinal glandular system is also well developed in 

 these animals ; the form of the glands differs pretty much from those 

 we have already seen : thus, in the aggregated glands of the Lion 

 (Fig. 292), each gland stands in a cup, or surrounded by a ditch, 

 which is filled with mucus-crypts, the gland itself being somewhat 

 conical in form, the top constituting the larger portion. 



800. But in addition to the aggregated, animals have, in their 



FIG. 291. FIG. 292. 



Ileum of a Lion. Feyer's glands, Ileum of ^ion. 



small intestines, glands of the same character and form, dispersed 

 widely, and found singly : these are the solitary glands. The large 

 intestine has its glands also, always however of the solitary kind, and 

 being in structure the exact converse of those we have yet examined. 

 The glands hitherto seen were evolved (opened, expanded), those to 

 be described are involute (to envelop, to cover with surrounding 

 matter) ; in other words, they are funnel-shaped cavities, excavated 

 as it were out of the mucous membrane. In the first, we saw the 

 outside in the last, the inside ; both these glands are really shaped 

 alike, but they are reversed in their position. 



801. Again, reference is made to the large intestine of the Lion 

 for the demonstration (Fig. 293) ; here the capillary structure of the 

 mucous membrane is everywhere seen ; it surrounds the cavities of 

 the solitary glands, and enters them to a certain depth. 



To render this more intelligible, a section of the last prepara- 

 tion is figured (Fig. 294). The capillary plexuses of the mucous 

 membrane are seen upon the upper surface, and descending for a 

 space into the cavity of the gland, and finally, its funnel-shaped inte- 

 rior is well shown. 



