NATURAL SCIENCES OF PHILADELPHIA. 369 



That this poisonous action of the extract of hemlock is clue to 

 impurities and not to the exceedingly small quantity of conia 

 which it contains, was shown by the following experiment: 



Exp. 4. Placed two young ailanthus plants in bottles, one bot- 

 tle containing a one-grain solution of conia, and the other con- 

 taining pure water. In three and a half days the plant placed in 

 water drooped, and on the fifth day it was dry and brittle, while 

 the plant placed in the conia solution did not droop until the 

 eighth day. 



This experiment, taken in connection with another which gave 

 similar results, proves that conia, instead of acting injuriously on 

 plants, really preserves them from decay. As the alkaloid had to 

 be dissolved in a small amount of alcohol, the thought suggested 

 itself that the preservative action was due to the alcohol; but, in 

 the experiments made by the writer to determine this point, it 

 was ascertained that alcohol, instead of acting as a preservator of 

 plants, really hastens their destruction, probably by coagulating 

 their albumem. 



Local Action. 



A study of the local action of the drug shows that it causes a 

 progressive loss of functional power in all the highly-organized 

 tissues with which it comes in contact. Nerve-centres, peripheral 

 nerves, muscles, both striated and unstriated, all succumb to it 

 alike. If such contact be not continued too long, the tissue may 

 recover, even after a total suppression of its function a proof that 

 the alkaloid exerts no destructive caustic influence upon the tis- 

 sues, as was claimed by Tan Praag. Excluding the burning pain 

 and the anaesthesia which follow, I have never observed any ac- 

 tion on the tongue even if the alkaloid was placed on this most 

 sensitive organ undiluted. 



In opposition to the above conclusions I must cite the state- 

 ment of Van Praag (Reil's Journal of Pharmacodynamic lift. i. 

 S. 33), who says that he found conia to act as a caustic when 

 locally applied. The following experiments prove the correct- 

 ness of the conclusions above given, and consequently the falsity 

 of Van Praag's conclusion. 



Exp. 5. Placed one grain of conia on my arm ; in two minutes 

 the spot was red and painful, but in five minutes on pricking the 

 spot with a needle no pain is produced ; the redness remained 

 several hours. 



