ABSORPTION. 195 



bloodvessels alone remained. These results were afterward corroborated 

 by Panizza, who succeeded in detecting the substance which had been 

 absorbed in the venous blood returning from the part. This observer 

 opened the abdomen of a horse, and drew out a fold of the small intes- 

 tine, about 20 centimetres in length (Fig. 63, a, a), which he included 



Fig. 63. 



PANIZZA'S EXPERIMENT. aa. Intestine, b. Point of ligature of mesenteric vein. 

 c. Opening in intestine for introduction of poison, d. Opening in mesenteric vein behind the 

 ligature. 



between two ligatures. A ligature was then placed (at 6) upon the 

 mesenteric vein receiving the blood from this portion of intestine; and, 

 in order that the circulation might not be interrupted, an opening was 

 made (at d) in the vein behind the ligature, so that the blood brought 

 by the mesenteric artery, after circulating 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 immediately afterward its presence was detected in the 

 venous blood flowing from the orifice at d. The animal, however, was 

 not poisoned, since the acid was prevented from gaining an entrance 

 into the general circulation by the ligature at 6. 



Panizza afterward varied this experiment in the following manner: 

 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 again allowed to pass 

 through the vessels, symptoms of general poisoning became manifest. 

 Lastly, in a third experiment, the same observer removed all the nerves 

 a'nd lacteal vessels supplying the intestinal fold, leaving the blood- 

 vessels alone untouched. Hydrocyanic acid, now being introduced into 

 the intestine, found an entrance at once into the general circulation, and 



