ABSORPTION FROM THE DIGESTIVE CAVITY. 443 



are of great importance, in showing the very marked influence which the state 

 of the stomach exercises upon the absorption of matters introduced into it. Not 

 less important, however, is the state of the vascular system in regard to turges- 

 cence or emptiness; for it was found by Magendie, that when he had injected 

 a considerable quantity of water into the veins of a dog, poison was absorbed 

 very slowly; whilst, if he relieved the distension by bleeding, there was speedy 

 evidence of its entrance into the circulation. The rapidity with which not only 

 aqueous but alcoholic liquids introduced into the stomach may pass into the 

 general circulation, has been shown by the experiments of Dr. Percy; 1 who 

 found that when strong alcohol was injected into the stomach of dogs, the ani- 

 mals would sometimes fall insensible to the ground immediately upon the com- 

 pletion of the injection, their respiratory and cardiac movements ceasing within 

 two minutes; and that on post-mortem examination in such cases, the stomach 

 was nearly empty, whilst the blood was highly charged with alcohol ; thus ren- 

 dering it highly probable, that not merely the final destruction of nervous power, 

 but the immediate loss of sensibility, was due to the action of alcoholized blood 

 upon the nervous centres. Finally, numerous experiments have been made by 

 various physiologists, which have demonstrated the absorption of alimentary and 

 other substances from the walls of the Stomach; these substances having been 

 prevented from passing into the intestine, by a ligature around the pylorus. 

 Now, as the Absorbent system does not present that peculiar arrangement in 

 the coats of the stomach, which it does in those of the intestinal tube, there 

 can be little doubt that the introduction of such substances into the system 

 must be effected chiefly, if not entirely, through the medium of its capillary 

 Bloodvessels. 



463. That the Bloodvessels of the Intestinal tube, also, largely participate in 

 the introduction of soluble alimentary matter into the system, has been clearly 

 proved by various observations upon the constitution of the blood of the mesen- 

 teric veins ( 167) ; these having shown, that after the digestion of albuminous 

 and farinaceous or saccharine substances, albuminose, dextrin, grape-sugar, and 

 lactic acid are detectible in that fluid, whose usual composition is greatly altered 

 by the presence of these substances, as well as by the augmented proportion of 

 water which it contains. We may consider the Sanguiferous vessels, then, as 

 affording the usual channel by which a large part of the nutritive materials are 

 introduced into the system ; but these are not allowed to pass into the general 

 current of the circulation, until they have been subjected to an important assimi- 

 lating process, which it appears to be one great office of the Liver to perform, 

 whereby they are rendered more fit for the purposes they are destined to serve 

 in the economy. Of this we shall presently have to speak ( 472). But the 



takes place, so that it passes into the renal vein, without reaching the heart. And he 

 asserts that a peculiar thickening of the muscular coat exists in the upper part of the 

 vena cava, whereby its contraction is occasioned; also that there are (in the horse at least) 

 direct passages by which a part of the portal blood may be discharged into the vena cava, 

 without passing through the liver. ("L'Union Medicale," 1849, No. 115.) Now, in the 

 first place, this hypothesis is not necessary to explain the facts ; for, as will be shown 

 hereafter ($ 509), there is evidence of the transmission of substances to other parts, with 

 at least as much rapidity as is indicated by their appearance in the urine. And, in the 

 second place, if the supposed reflux really took place, it must affect the whole venous cir- 

 culation of the trunk and lower extremities, except such as the vena azygos and a few 

 other small channels could provide for ; and must occasion (to make good the conditions 

 of the problem) not merely a stagnation, but an absolute reflux, so that the veins are meta- 

 morphosed into arteries, and the arteries into veins. How the vis d tergo, originally de- 

 rived from the heart, can thus be strong enough at the very end of the systemic circulation, 

 not merely to neutralize, but actually to overcome, the force which it exercises almost 

 close to the heart, M. Bernard has not informed us. 



1 "Experimental Inquiry concerning the Presence of Alcohol in the Ventricles of the 

 Brain," p. 61. *"" " 



