IS OBTAINED WHOLLY BY RESPIRATION. 899 



plained the chemical source of animal heat than 

 any of his predecessors, and triumphantly refuted 

 many absurd hypotheses ; candour obliges me to 

 say, that he has overlooked some of the most im- 

 portant facts connected with the theory of respira- 

 tion. For example, he maintains in various parts 

 of his late work, that atmospheric oxygen is con- 

 veyed from the lungs to every part of the body, 

 where it unites with carbon and hydrogen to form 

 carbonic acid and water: that " the globules of 

 the blood, which can be shewn to take no share 

 in the nutritive process, serve to transport the 

 oxygen, which they give up in their passage 

 through the capillary vessels." (Op. cit. p. 60.) 

 But that atmospheric oxygen combines with 

 carbon and hydrogen in the lungs, is evident 

 from the fact, that in mammalia the temperature 

 of blood is from 1 to 3 higher in the left ventricle 

 of the heart, pleura, and carotid arteries, than in 

 the right ventricle of the heart, vena cava, or 

 jugular veins, as noticed by Hippocrates, Black, 

 Haller, Plenck, and Menzies, but fully demon- 

 strated by the numerous and careful experiments 

 of Dr. John Davy, which I have verified by 

 many observations on recently killed sheep and 

 oxen. I have also proved that, during the pas- 

 sage of arterial blood through the systemic capil- 

 laries, the caloric obtained by respiration in the 

 lungs is employed in combining a portion of its 

 organic particles with the solids, in maintaining 



