166 ABSORPTION. 



in the intestinal capillaries, passed out at the opening, and was 

 collected in a vessel for examination. Hydrocyanic acid was then 

 introduced into the intestine by an opening at c, and almost imme- 

 diately afterward its presence was detected in the venous blood 

 flowing from the orifice at d. The animal, however, was not poi- 

 soned, since the acid was prevented from gaining an entrance into 

 the general circulation by the ligature at b. 



Panizza afterward varied this experiment in the following man- 

 ner : Instead of tying the mesenteric vein, he simply compressed it. 

 Then, hydrocyanic acid being introduced into the intestine, as above, 

 no effect was produced on the animal, so long as compression was 

 maintained upon the vein. But as soon as the blood was allowed 

 to pass again through the vessels, symptoms of general poisoning 

 at once became manifest. Lastly, in a third experiment, the same 

 observer removed all the nerves and lacteal vessels supplying the 

 intestinal fold, leaving the bloodvessels alone untouched. Hydro- 

 cyanic acid now being introduced into the intestine, found an 

 entrance at once into the general circulation, and the animal was 

 immediately poisoned. The bloodvessels, therefore, are not only 

 capable of absorbing fluids from the intestine, but may even take 

 them up more rapidly and abundantly than the lacteals. 



These two sets of vessels, however, do not absorb all the aliment- 

 ary matters indiscriminately. It is one of the most important of 

 the facts which have been established by modern researches on 

 digestion that the different substances, produced by the operation of 

 the digestive fluids on the food, pass into the circulation by different 

 routes. The fatty matters are taken up by the lacteals under the form 

 of chyle, while the saccharine and albuminous matters pass by ab- 

 sorption into the portal vein. Accordingly, after the digestion of a 

 meal containing starchy and animal matters mixed, alburninose and 

 sugar are both found in the blood of the portal vein, while they can- 

 not be detected, in any large quantity, in the contents of the lacteals. 

 These substances, however, do not mingle at once with the general 

 mass of the circulation, but owing to the anatomical distribution of 

 the portal vein, pass first through the capillary circulation of the 

 liver. Soon after being introduced into the blood and coming in 

 contact with its organic ingredients, they become altered and con- 

 verted, by catalytic transformation, into other substances. The 

 albuminose passes into the condition of ordinary albumen, and 

 probably also partly into that of fibrin ; while the sugar rapidly 

 becomes decomposed, and loses its characteristic properties; so 



