29. Very different notions have been entertained concerning the nature of these villosities: they have been considered, in the œsophagus and in the stomach, as destined to the exhalation of the gastric juice, in the intestines as serving for the absorption of chyle, &c. But (1) It is difficult to conceive how an organ, so nearly similar throughout its extent, should fulfil, in different parts, such different functions; I say so nearly similar, because we know, that the villosities of the small are more prominent than those of the large intestines. (2) What would be the functions of the villosities of the pituitary membrane, of the internal coat of the urethra, and of the bladder, if they had no connection with the sensibility of these membranes. (3) The microscopic experiments so boasted of by Leiberkuhn, on the erection of the intestinal villosities, have been contradicted by those of Hunter and Cruikshank, and, above all, by those of Hewson. I can assert, that I have never seen any thing of the kind on the surface of the small intestines during the absorption of chyle, and yet it appears to be a thing that cannot vary in different examinations. (4) It is true that these intestinal villosities are everywhere accompanied by a vascular web, which gives them a colour very different from that of the cutaneous papillæ; but the nonappearance of the cutaneous web is occasioned only by atmospherical pressure, by means of the contraction that it produces in the minute vessels: see, for instance, the newly-born infant; its cutaneous surface is as red as that of its mucous membranes, and if the papillæ were a little more elongated the skin would exactly resemble the internal surface of the intestines: moreover, who does not know, that the vascular web surrounding the papillæ is rendered so apparent by fine injections as entirely to change the colour of the skin? 30. That in the stomach this vascular web exhales the gastric juice, and in the intestines it is interlaced with the origin of the absorbents, so that they embrace the villosities, are facts that we must admit, after the experiments and observations of the anatomists, who in these times have been engaged with the lymphatic system: but that does not contradict the assertion, that the bases of these villosities are nervous, and perform the same functions only on the mucous membrane as the papillæ do on the cutaneous organ. This view of them, by explaining their existence as observed generally over all the mucous surfaces, appears to me much more conformable to the plan of nature than to suppose that they perform, in their different parts, diverse and frequently opposite functions.