196 THE LAWS OF ORGANIC 



fore cannot be expected to excite the contrac- 

 tions of the heart ; and as it is not propelled 

 throughout the arterial system with regularity or 

 force, the remote arteries, from the want of the 

 ordinary vis a tergo, and the accustomed quantity 

 and qualities of the vital fluid, to stimulate these 

 powers, on which their pulsations depend, exhi- 

 bit a feeble or almost imperceptible action. 



CCXX. When these symptoms cannot pro- 

 ceed any farther without endangering life, they 

 are by degrees mitigated by the reaction of the 

 system. It was shown by HUNTER, when an 

 animal is cooled down to a point much lower 

 than what is natural, that the intense cold is 

 counteracted by the evolution of a greater quan- 

 tity of heat ; and it is also stated by Dr ED- 

 WARDS, who has paid considerable attention to 

 this subject, that it arises from the exertions of the 

 animal to escape or remove itself from the de- 

 pressing agent, thereby exciting the respiratory 

 functions to the more perfect oxygenation of the 

 blood ; and it is to a similar cause, conjoined with 

 the means we employ to promote the same result, 

 that we are to attribute the return of the system 

 to its normal state. In support of the general 

 view brought forward, I may allude to the suc- 

 cess of depletion in the cold stage of intermittent, 

 as fully proved by Dr MACKINTOSH of 

 burgh, in a variety of cases. 



