42 ORGANS OF DIGESTION. 



leries scarcely makes itself visible among these veins when they 

 are properly injected, a straggling branch only here and there 

 exhibiting itself. The arborescence of the arteries is confined 

 to the level beneath the venous intertexture, and is there deve- 

 loped to an extreme degree of minuteness, being intermixed 

 with corresponding venous ramuscles, generally larger and more 

 numerous than the arteries themselves. This arrangement seems 

 to occur in the surface of the cellular coat which makes the 

 base or ground of the mucous. The fine venous trunks of this 

 deeper layer have their originating extremities bent vertically 

 towards the cavity of the gut, and by that means receive the 

 blood of the first venous intertexture or layer, as the petrou-s 

 sinuses join the cavernous, or the veins of the penis arise from 

 its spongy structure. The meshes of the first venous intertex- 

 ture are exceedingly minute, and vary in a characteristic man- 

 ner in the stomach, small intestines and colon. This intertex- 

 ture is very different in its looks fro,m a common vascular anas- 

 tomosis, and produces in the colon an appearance resembling 

 a plate of metal pierced with round holes closely bordering upon 

 each other; these holes constitute, in fact, follicles or gaping 

 orifices, the edges of which are rounded off, and their depth is 

 that of the thickness of the venous anastomoses; being bounded 

 below by the arterio venous layer, and by the cellular coat of 

 the part. Nothing short of an entirely successful injection wi.ll 

 exhibit this venous anastomosis as described; and it may be 

 seen either by injecting a vein, or an artery provided the injec- 

 tion passes from the artery* into the veins, but the latter process 

 is the least desirable, because we lose the benefit of a distinc- 

 tion of colour between the two sets of vessels. 



Ordinary modes of examination give no evidence of the exis- 

 tence in the alimentary canal, from the cardiac orifice, of the 

 stomach to near the anus, of an epidermis; on the contrary, they 

 rather lead to. a belief of its being absent, in consequence of the 

 softness, tenuity, and transparency of the mucous membrane; 

 but that it is really present, may be proved by the following 

 process: Tear off the peritoneal coat of a piece of small intes- 

 tine invert the part and inflate it to an, emphysematous condi- 

 tion; the epidermis will then be raised as a very thjn pellicle, 

 and may be dried in that state; but as this pellicle retains the 

 air, we hence infer that it lines the folliclesand is uninterrupted 



