126 THE LAWS OF ORGANIC 



CXXXI. From these tables it is evident that 

 young animals do not indicate a less degree of 

 temperature than adults, if they are examined 

 under circumstances favourable to the sensibility 

 of their frame, or in situations not liable to great 

 changes. It is unnecessary to bring forward the 

 particular details of Dr EDWARDS to shew that 

 young animals bear cold with less facility than 

 adults ; the fact is undoubted, but is not to be 

 explained by supposing the source of generating 

 heat less in the former than in the latter. 



CXXXII. The lungs are to be regarded as 

 the cause of animal temperature. We observe 

 that this is modified very much by the altera- 

 tions which the lungs undergo ; at one time it is 

 much increased, at another equally diminished, by 

 disease or general affections. The manner in 

 which the greater number of these causes oper- 

 ate has been explained in the previous chapters, 

 particularly in the first, in which I endeavoured 

 to shew that animal heat is in the inverse ratio to 

 the quantity of blood exposed to the action of the in- 

 spired air ; and in the preceding chapter on the 

 distribution of the blood at different ages, I have 

 also pointed out the great changes of which this 

 is susceptible, from the increased activity or more 

 complete development of internal organs. 



CXXXIII. The blood in a young animal 

 being more generally diffused throughout the 

 system, the surface of the body, at this time of 



