3go8 ESSAYS anp OBSERVATIONS 
fhew its influence upon the motion of the 
heart. 
1. Havina injected a folution of opi- 
um in water into the ftomach and guts of 
a frog, I obferved that, in little more than 
half an hour, it feemed to have loft all 
power of motion, as well as feeling ; for 
there was no contraction produced in the 
mufcles of its limbs and trunk by irrita- 
ting them. I opened the thorax an hour 
after the injection, and found the heart, 
inftead of between 60 and 70, making on- 
ly 17 pulfations in a minute, The auri- 
cle, which was much diftended with blood, 
always contracted firft, and after it the 
ventricle. 
2. A frog continued to move its limbs, 
and leap about for above an hour after I 
had cut out its heart, and was not quite 
dead after two hours and a half. 
Five minutes after taking out the heart 
of another frog, I injected a folution of o- 
pium into its ftomach and guts. In lefs 
than half an hour, it feemed to be quite 
dead ; for neither pricking nor tearing its 
mutfcles 
ct ee 
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