vol,. LXX.] PHILOSOPHICAL TRANSACTIONS. ()45 



son, which is noxious when taken in large doses, make me think that the poison 

 of the viper, though it is innocent when taken by the mouth in a small quantity, 

 may yet be mortal when taken in a greater quantity. That torpor which it ex- 

 cites on the tongue, and which continues so long, is enough to convince us, 

 that it is not quite inactive, and that it may really be fatal when taken in a large 

 quantity. I intend to try this experiment on some future occasion, when I pro- 

 pose to give the collected poison of 18 or 20 vipers to a small animal when its 

 stomach is empty, and I dare venture to prophecy, that it will die; for since a 

 very small dose can take away motion and sensation from the tongue, or, in 

 other words, deprive that organ of its principles of life, a greater quantity ought 

 to destroy those of the organs more essential to life itself. If we consider that 

 poison taken in by the mouth must extend itself over a very large surface which 

 is always moist, and mix itself with the food in the stomach, and that the ab- 

 sorbing vessels are extremely small, it will no longer seem strange that it is not 

 noxious when taken in a small quantity, which we have just seen to be the case 

 with the American poison. 



I began my experiments on the activity of this poison by wounding different 

 parts of animals with a lancet wetted in the poison dissolved in water. I wounded 

 a small Guinea-pig with it in the thigh 3 times at different intervals. The lancet 

 was full of poison, yet the animal suffered no harm. I made the same trial on 

 3 other little pigs and a rabbit, but none of them either died or suffered any in- 

 jury. In all these cases the blood flowed evidently from the wounds: from which 

 I suspected that the poison could not diffuse itself, but that it was driven back, 

 as I had observed in the case of the poison of the viper, which, for this reason, 

 is frequently harmless. 



My suspicion was soon confirmed by the following experiments. 1 soaked a 

 single thread in the poison, and passed it through the skin of a Guinea-pig near 

 one of the nipples, but yet no disorder followed. I then soaked another thread 

 thrice doubled, and let it first dry a little, for fear the poison should remain be- 

 hind on the skin, in drawing the thread through it. I passed it through the 

 skin of the thighs of a small rabbit near the belly; in 6 minutes the rabbit began 

 to shake and show signs of weakness. In another minute it fell down motion- 

 less, appeared convulsed at intervals, and was quite dead in (J minutes more. I 

 repeated this same experiment, of the soaked double thread, on 2 other rabbits, 

 and on 3 Guinea-pigs; all of which fell down, and were convulsed in 6 or 7 mi- 

 nutes, and died within the half hour. 



I had the curiosity to try if the American poison could communicate itself to 

 animals, and kill them, when applied to the skin barely scratched, or scarcely 

 wounded with the point of a lancet. I had observed at Paris, that the poison 

 of the viper communicated a local disorder in such cases, and that it affected and 



