AND ANIMAL LIFE. 129 



of Dr EDWARDS, although he assigns lessened 

 production of heat as the cause. The principle 

 I propose immediately becomes of practical uti- 

 lity, whereas those views which have hitherto 

 been given as explanatory of the same phenome- 

 na have indeed little reference to the different 

 states of the system in health or disease. We 

 now understand that young animals have an 

 equal, if not superior faculty of producing heat 

 to adults, and yet, at the same time, have not the 

 power of bearing the same severity of cold. The 

 true reason of this being known, we shall be en- 

 abled to regulate the application of heat and cold 

 to the body, from a knowledge of the principal 

 conditions of the system on which they have to 

 act ; and we shall also be enabled to judge accur- 

 ately of the beneficial or injurious influence of 

 these, from a knowledge of the dependence of the 

 digestive and assimilating functions on the tem- 

 perature of the blood and the mode of its distri- 

 bution. 



CXXXVIII. During the winter of 1828-29, 

 the cold in some nights was extremely severe. The 

 thermometer, in the room in which I kept the 

 rabbits for experiments, was often as low as 37 ; 

 in an apartment adjoining to this water was fro- 

 zen to a considerable thickness. During the 

 continuance of this weather I lost a great num- 

 ber of young rabbits, and the old occasionally 

 died ; and all, except the most vigorous, were far 



I 



