AND ANIMAL LIFE. 141 



CLI. In advanced life the constitution is high- 

 ly sensible to cold, but this susceptibility is not 

 referrible to a state of the circulation analogous 

 to that which predominates in the infant, but 

 depends on other principles. At this period the 

 lungs and the heart do not exhibit that energy 

 which characterized their action at the com- 

 mencement of manhood ; the blood is trans- 

 mitted sparingly, and with little force, to the 

 surface of the body ; and from this cause the 

 capillary vessels possess little stimulus to resist 

 the influence of cold, and, therefore, if this be 

 applied, it is quickly accompanied with disagree- 

 able sensations. 



CLII. From the preceding observations we 

 may draw the following conclusions : 



1. That young animals possess an equal, if not superior, 



faculty to adults for the generation of animal heat. 



2. That the facility with which an animal bears exposure 



to cold, is regulated by the distribution of the blood 

 at different periods of life. 



3. That individuals of the same class, and of the same age, 



differ in their power of resisting cold according 

 to the character of the circulation and the force with 

 which the blood is propelled by the heart. 



4. That the ease with which animals are recovered after 



exposure to cold is modified by the previous condi- 

 tion of the circulation, and consequently is not regu- 

 lated by their different powers of generating heat. 



5. That the more sudden diminution of the temperature 



in summer, on the application of cold, is not explain- 



