INTRODUCTORY OBSERVATIONSo Ixiil 



fame is an invariable rule with the reproduftions 

 of mutilated members. — ^Two general clalTes of 

 animals are the cold and warm blooded. The lat- 

 ter always remain nearly at the fame degree of 

 heat, that is, commonly between 96*^ and 104° ; 

 though the furrounding medium jQiould be very 

 far above or below thefe limits. Thofc v/ith 

 cold blood are not far from the temperature of 

 the furrounding medium ; and if it increafes to a 

 great degree, or falls very low, a material change 

 is produced on their fyftem. Thefe animals feem 

 to enjoy feveral eminent prerogatives refpefting 

 their individual fafety ; and among others, that of 

 reprodu6lion. Few material parts of warm blood- 

 ed animals are regenerated ; while of fome cold 

 blooded animals, there are few that are not re- 

 produced. But heat is equally eflential to this 

 regeneration as it is to propagation and exclu- 

 fion. Although we divide animals into cold and 

 warm, cold is but a relative expreffion j for, ia 

 the total abfence of heat, life would be extinft j 

 and we always fee it deftroyed by a confiderable 

 degree of cold. 



Even in warm blooded animals, there are im- 

 portant reproductions continually going on, per- 

 haps from the moment of birth until death. The 

 fluids are continually walled and repaired. The 



infenfible 



