AND ANIMAL LIFE. 183 



In the cold stage of fevers the surface of the 

 body is collapsed and pale, and the blood is evi- 

 dently concentrated in the internal organs con- 

 tained in the three great cavities of the body. 

 The difficulty of breathing, and oppression in the 

 chest, shew that the lungs and heart are implica- 

 ted ; the pallid aspect of the face, the dulness of 

 the eye, and the pain of the head, or occasional 

 delirium, prove the brain to be affected, and the 

 enlarged liver and spleen demonstrate a similar 

 condition of the abdominal viscera. Since the 

 lungs have more blood than is natural, it is ma- 

 nifest that his idea of a diminished quantity pass- 

 ing through them has little relation to the quart* 

 tity on which the air has to act ; and as this is 

 augmented, the consequences are in harmony 

 with the principles stated in the first chapter, viz. 

 That animal heat is not in the direct ratio of the 

 quantity of oxygen inhaled, but in the inverse ratio 

 of the quantity of blood exposed to this principle. 



CCIII. It is stated by CRAWFORD, that the ca- 

 pacity of the arterial blood for caloric is greater 

 than that of the venous ; and the opinion beauti- 

 fully illustrates his ideas of animal heat, as he 

 imagined this to be extricated in the minute ca- 

 pillary vessels of the system, and not in the lungs ; 

 and it also removes the difficulties which were 

 opposed to the views of Dr BLACK, which suppos- 

 ed the evolution of this principle to take place in 

 the lungs. This important point has been inves- 



