gro ESSAYS anp OBSERVATIONS 
4. IMMEDIATELY after decollating a 
frog, I deftroyed its fpinal marrow, by 
pufhing a {mall probe down thro ‘its {pine, 
which occafioned ftrong convulfions of all 
- the mufcles, efpecially thofe of the infe- 
rior extremities. Ten minutes after this, 
I opened the thorax, and found the heart 
beating at the rate of 45 times in a mi- 
nute. Sixteen minutes after decollation, 
it moved 40 times ina minute. After 
half an hour it made’36, and after fifty 
minutes only 30 pulfations in the minute, 
which were now alfo become very {mall 
and feeble. 
N.B. Wen l nheaed the thorax of 
another frog immediately after decolla- 
tion, and deftroying its fpinal marrow, I 
obferved its heart beating at the rate of 
60 in a minute, which is four or five pul- 
{ations lef than I have generally feen the 
hearts of frogs make in that time, when 
their thorax was opened without decolla- 
tion. 
5. AT 
