AND ANIMAL LIFE. 149 



teristic of winter, disturbs it by re-establishing 

 abruptly its former state. 



In both instances the physical conditions of the 

 system are the same, an enlarged surface of blood 

 zs subjected to the agency of cold, without the capa- 

 bility of the one being proportioned to the circum- 

 stances of the other. 



CLX. The knowledge of the opposite states of 

 the sanguiferous system, at various seasons, ex- 

 plains, in a satisfactory manner, the powers of vi- 

 tality in resisting the effects of cold. We are not 

 necessitated to have recourse to the supposed ex- 

 istence of an ideal principle, and, by endowing this 

 with convenient properties, to give the semblance 

 of an explanation of the phenomena of organic life. 

 Nor are we compelled to grant to Dr EDWARDS 

 that the greater or less consumption of oxygen, 

 at the various seasons, is the cause why the frame 

 conforms to external circumstances. This opi- 

 nion, and many others connected with it, have 

 been shewn to be incorrect in the preceding chap- 

 ter. We perceive the vegetable and animal to pos- 

 sess corresponding general characters of circulation 

 at different seasons of the year ; and we also re- 

 mark, that these characters are influenced by ex- 

 ternal causes in the same way. 



CLXI. As we proceed from south to north, 

 the constitution of man changes with the chang- 

 ing climates ; his susceptibility of cold is 



