316 ESSAYS anp OBSERVATIONS 
pat four, z. e. five hours and forty four 
minutes after the frog was taken out of 
the folution, the auricle of its heart beat 
9 times in fixty four feconds. 
8. I laid bare the abdominal mufcles 
and thorax of another frog, and, at four- 
teen minutes paft eight in the morning, 
immerfed it as above in a turbid folution 
_of opium. Fourteen minutes paft nine, 
I tock it out of the folution, and laid open 
its thorax and’ pericardium ; after which 
the heart began to beat at the rate of nine 
times inaminute: But the auricle, which 
was greatly diftended with blood, made 
no motion, except in fo far as it was agi- 
tated a little by the pulfation of the heart: 
Nor were the mufcles of the legs or thighs 
brought into contraction by cutting or 
tearing their fibres. At half an hour paft 
nine the heart beat only 7 times in a mi- 
nute; and the auricle, which was now 
pretty empty of blood, and, in place of 
it, filled with air, had a pulfation as well 
as the heart. Thirteen minutes before 
ten, 7..¢. thirty three minutes after the 
irog was ‘taken out of the folution, the au- 
; ricle 
