442 Or ABSORPTION AND SANGUIFICATION. 



by something like a continuous membrane (Fig. 5); and it was doubtless this 

 which was mistaken by Prof. Goodsir for the proper basement-membrane that 

 underlies the epithelium-cells. It may, then, be stated with some confidence, 

 that the epithelium-cells covering the extremities of the villi are the real instru- 

 ments in the selection and absorption of the materials of the chyle; and that, 

 drawing these into their own cell-cavities, they subsequently deliver them up to 

 the lacteals, by which they are carried towards the centres of the circulation. 

 And further, that although it may be true that the epithelium-cells are some- 

 times cast off in considerable quantities, in certain disordered states of the 

 mucous membrane (as in cholera), yet there is no evidence of its being thus 

 exuviated in health; the appearances which have led to the idea that such 

 exuviation is a regular occurrence, being partly dependent upon the facility with 

 which the villi are denuded of them by maceration or manipulation. 



462. In regard to the degree in whiBh the function of Nutritive Absorption 

 is performed by the Lacteals and by the Sanguiferous system respectively, con- 

 siderable difference of opinion has prevailed. When the Absorbent vessels were 

 first discovered, and their functional importance was perceived, it was imagined 

 that the introduction of alimentary fluid into the vascular system took place by 

 them alone. A slight knowledge of Comparative Anatomy, however, might 

 have sufficed to correct this error; since no lacteals exist in the Invertebrated 

 animals, the function of Absorption being performed by their mesenteric blood- 

 vessels only, whence it is evident that these do possess the power of absorption : 

 and it is scarcely to be supposed that they should not exercise this power in 

 Vertebrated animals also, since their disposition on the walls of the intestinal 

 cavity is obviously favorable to it. On the other hand, the introduction of a 

 new and distinct system of vessels would seem to indicate, that they^ must have 

 some special purpose; and there can be no doubt that the absorption of a par- 

 ticular kind of nutritive matter is that for which they are designed. That 

 Absorption is effected, to a very considerable amount, by the agency of the 

 Bloodvessels, is shown by the readiness with which aqueous fluids, and even 

 alcohol, are taken up from the parietes of the stomach, and are carried into the 

 general circulation. Thus in a case of extroversion of the bladder, observed by 

 Mr. Erichsen, 1 in which the urinary secretion could be collected immediately 

 on its passing from the kidney, when a solution of ferrocyanide of potassium 

 was taken into the stomach, this salt was detected in the urine in one instance 

 within 1 minute, and in three other instances within 2 minutes. In all these 

 cases, however, the stomach may be presumed to have been empty, and the vas- 

 cular system in a state of aptitude for absorption; since the experiments were 

 made either after a long fast, or at least four hours after a light meal. When, 

 on the other hand, the salt was introduced into the stomach soon after the in- 

 gestion of alimentary substances, a much longer period elapsed before it could 

 be detected in the urine; thus, when a substantial meal had been taken two 

 hours previously, the interval was 12 minutes; when tea and bread-and-butter 

 had been taken one hour previously, the interval was 14 minutes ; a similar 

 meal having been taken twenty -four minutes previously, the interval was 16 

 minutes; when only two minutes had passed since the conclusion of such a 

 meal, the interval was 27 minutes ; and when a solid meal had been concluded 

 just before the introduction of the salt, the interval was 39 minutes. 2 These facts 



1 "Medical Gazette," vol. xxxvi. p. 363. 



2 The great rapidity with which soluble salts, introduced into the stomach, make their 

 appearance in the urine, has led M. Cl. Bernard to think that some more direct channel 

 must exist for their passage from the stomach to the kidneys, than that which the ordi- 

 nary current of the sanguiferous circulation affords. And he has advanced the extraordi- 

 nary doctrine, that whilst absorption is going on, there is a constriction of the vena cava 

 above the entrance of the hepatic vein, whereby a reflux of the blood discharged by it 



