,404 On opium. 



The length of time in which contraftions may be indtt- 

 cedby metallic fubftances, in the frog, is much diminilhed 

 by the application of opium. In 20 minutes after the death 

 of this frog 1 could not produce any ; now they may be in- 

 duced at the expiration of 48, 72 and even a greater num- 

 ber of hours, in a frog killed by cutting off, or crufliing 

 the head ; as the experiments of Dr. Fowler on animal elec- 

 tricity evincq., 



Experiment 54^ 



Augull a2d. At 10 minutes after 3 o'clock, I expofed 

 to view the brain of a frog, and put a few drops of the aque- 

 ous folution A. upon it. By a want of attention to the 

 motions of the frog, the greateft portion of it was fpeedily 

 loft. In 5 minutes he was very lively. In 10 minutes 

 the fame. At 30 minutes after 3, I introduced a fecond 

 portion with greater care, which almoft inftantly feefned to 

 affe£t him ; for inftead of fupporting himfelf as ufual upon 

 his leg&, he lay upon his abdomen. In 5 minutes his left 

 leg feemed paralized, and he tumbled about with a fort of 

 convulfive motion. In 10 minutes he was more affected. 

 A pointed inftrument fcarcely caufing him to move; and 

 his motions were chiefly confined to his upper extremities. 



In 20 minutes he appeared to be quite dead. On opening 

 the thorax I found the heart pulfating vigoroufly 56 times 

 in a minute. In 15 minutes from this time it beat 48. In 

 this frog, the contradions produced by zinc and filver were 

 by no means fo vigorous, as in thofe killed without the ap-. 

 plication of opium. 



Ex-PERTMENT ^^. 



By way of a comparative experiment, on the 26th of Au-. 

 guft, I injeded foroe drops of the aqueous folution of fo«- 



mon 



