ANATOMY OF THE MUCOUS COAT. 43 



by any perforations. This epidermis, if the part be previously 

 injected perfectly, shows dots of injecting matter like those left 

 in the rete mucosum upon a minute injection of the skin, but no 

 arborescence if it be raised up from the veins by the inflation 

 stated. In so doing the villi disappear, are in fact unfolded. 



The villi cannot be seen to any advantage except they be 

 erected by an injection, in which case those of the upper part 

 of the small intestines are found to run into each other very 

 much like the convolutions of the cerebrum, and to press upon 

 each other's sides in the same way. Some of them, however, 

 are merely semi-oval plates, the transverse diameter of which 

 exceeds the length or elevation. At the lower end of the small 

 intestine they became simply conical projections, somewhat 

 curved, with the edges bent in or concave, and they retain this 

 mechanism until they entirely disappear near the ileo-colic valve. 

 In the whole length of intestine there is, however, every 

 variety of shape, from oblong curved and serpentine ridges, to 

 the laterally flattened cone standing on its base; the first condi- 

 tion changing gradually to the last in the descent of the bowel. 

 Conformably to this definition of villi, none exist either in the 

 stomach or colon, for there we have only the venous mesh. 

 The villi of the jejunum are about the thirtieth of an inch high, 

 and those of the ileum about one-sixtieth. 



In the ileum, the superficial venous layer has great regularity 

 and the conical villi stand out beautifully from its anastomoses, or 

 in equivalent language, from the divisions of the follicles. In 

 the upper part of the small intestine the follicles are in equal 

 number to what they are in the ileum; the regularity of their 

 arrangements being interrupted by the long serpentine and oval 

 villi; but invariably the same venous intertexture exists arid 

 forms, in both, the chief bulk of the villi, by passing into them. 

 In the stomach the follicles vary much in size, and there is 

 an arrangement whereby many of the smaller ones are seen to 

 open into the larger: on an average about two hundred and 

 twenty-five are found upon every square of one eighth of an inch, 

 which would give of course to an inch square sixty-four times 

 that amount, or fourteen thousand four hundred follicles; and 

 conceding the whole stomac-h to present an area of ninety 

 inches, which is probably below the .mark when this organ is 

 moderately distended, as exhibited ia the preparation upon 



