(364 PHILOSOPHICAL TRANSACTIONS. [ANNO 1780. 



proving fatal to all sorts of animals. But how is it always mortal in so short a 

 time, when taken by the mouth, and admitted into the stomach, where we do 

 not suppose there are any vessels capable of receiving it ? This difficulty re- 

 quires some further experiments. We ought to examine what effects it pro- 

 duces when applied immediately to the nerves, and when introduced into the 

 blood, without touching the parts which are cut. For this purpose, I made use 

 of large rabbits, and performed the experiments on their sciatic nerves, in the 

 same manner as I had done with the poison of the viper and the American 

 poison. I shall here transcribe only one experiment, omitting the rest for the 

 sake of brevity, not thinking them necessary after tlie great number which I 

 have already related on the nerves. 



Having detached the sciatic nerve of a large rabbit for above an inch and a 

 half, I introduced under it a wrapper of very fine linen, l6 times doubled, that 

 the parts below it might not be penetrated by the water of the Lauro-Cerasus. 

 I then wounded the nerve with many strokes of the lancet in the longitudinal 

 direction, and covered all this wounded part, which extended above 8 lines in 

 length, with a roll of cotton of 3 lines in thickness, well steeped in the laurel- 

 water. More than 1 5 drops of the water were wanted to moisten tlie cotton, 

 and this water communicated itself directly by the wounds to the medullary sub- 

 stance of the sciatic nerve. I covered the whole about a minute after with 

 new rags, so that it was impossible for the laurel-water to communicate with the 

 parts below it or near it. Having sewed up the external skin, and left the 

 animal at liberty, it seemed not to be in the least affected, neither then nor after- 

 wards. It ran about, and eat, and was as lively as ever. In short, the animal 

 was not sensibly affected in this way by this poison, which kills so quickly when 

 it is taken in by the mouth. This case, as well as many others, is very similar 

 to those of the poison of the viper and of the American poison ; and it shows, 

 that the water of the Lauro-Cerasus applied immediately on the nerves, and so 

 insinuated into the medullary substance of them, is not at all poisonous ; conse- 

 quently, that it does not act on the nerves, however applied externally. 



After so many experiments, as have been related in the course of this essay, 

 on the poison of the viper, and on the American poison, a still more powerful 

 one than the former ; and after having seen that neither of these 2 poisons act 

 on the nerves, when applied immediately to them, while they instantly kill very 

 strong animals when introduced into the blood ; nothing was more natural than 

 to conclude, that the poison of the Lauro-Ccrasus, which is equally innocent 

 with the others when applied to the nerves, would also prove mortal when intro- 

 duced into the blood : experience however shows quite the contrary ; so true is it 

 that we ought to mistrust analogy, even when it appears most uniform. I intro- 

 duced the water of the Lauro-Cerasus into the jugulars of a large rabbit, to the 



