%()6 ESSAYS AND OBSERVATIONS 



2. The ventricle of the heart of a full 

 grown frog contrads about 58 times in 

 a minute. , 



3. After the ventricle of the heart is 

 cut off, the animal can move about, for 

 an hour, and is evidently fenfible of in- 

 jury for half an hour longer ; though the; 

 motion of the blood ceafes, in the fmall 

 vefiels, as foon as the heart is cut out. 



4. If tlie circulation is ftopt in the 

 hind legs only, the animal can move them 

 above an hour and a half, and is very fen- 

 fible of injury done to them for four hours. 



5. Though all the nerves of the hind 

 legs be cut, or the pofterior half of the 

 fpinal marrow from which they rife hd* 

 deftroyed, and the whole hind legs be in- 

 flantly rendered infenfible and motion- 

 lefs ; yet the rapidity of the circulation of 

 the blood in the feet is not obfervably 

 kffened after feveral months, and the ab- 

 iorbent veffels, after that time, greedily 

 take in fluids applied to the fkin. 



6. Though the brain and fpinal mar- 

 row, or origin of all the nerves, be de- 

 ftroyed > yet the heart continues to be di- 

 lated 



