

ANIMAL HEAT. 341 



enabled to prove satisfactorily that the heat produced by the 

 combustion of the hydrogen and carbon of the food is suffi- 

 cient . to account for all the animal heat; where 'this heat 

 varies, it is always found that some excess or deficit of com- 

 bustible material has occurred in the animal economy. 



As to the exact region in which these combustions take 

 place, we have seen, in reference to respiration, that their 

 seat is not in the lungs, but in the capillaries, in the very 

 depth of the tissues. 1 We know, besides, that the venous 

 blood is generally the warmest ; the contact with the air in 

 the lungs which renders it arterial chills it slightly. The 

 greater the combustion in an organ, the warmer* will be 

 the blood that flows from it; as, for instance, the blood of the 

 hepatic veins and the venous blood of a muscle when con- 

 tracted. All physiologists are now agreed as to the complex 

 nature of the phenomena producing animal heat. The only 

 point upon which they differ in regard to it is the relative 

 importance of the reactions which take place in the blood, 

 and those which have their seat in the tissues. Pasteur, 

 Blondeau, and Camille Saint-Pierre give the supremacy to 

 the former. 2 Bernard recognizes, almost exclusively, not 

 only the importance, but the existence, of the latter. He 

 maintains that heat is engendered in the deepest part of the 

 organs, in close contact with the histological elements, by 

 means of the chemical reactions by which their nutrition 



1 A recent observation by M. Laboulbene seems, at first sight, 

 worthy of notice, in reference to the dispute regarding the seat of 

 respiratory combustion. Being desirous of ascertaining, in cases 

 of thoracentesis, the effect to be produced by taking away the fluid 

 which overflows into the pleural cavity, M. Laboulbene performed 

 this operation, and found that the temperature invariably rises after 

 it. This rise is explained by the changes produced in the state of the 

 respiratory organs by the withdrawal of the fluid. After the opera- 

 tion the lung resumes its functions, in the discharge of which it had 

 been hindered by the compression produced by the overflow of the 

 fluid: the air again freely penetrates the pulmonary vesicles, as is 

 shown by the disappearance of the dulness, and the presence of the 

 respiratory murmur by means of auscultation. This increase of pul- 

 monary activity, however, does not immediately precede the rise in 

 the temperature. The entrance into the lung of a larger quantity 

 of air imparts to the blood (the red globules) a greater proportion of 

 oxygen, and thus enables them to excite the inward processes of 

 nutrition and combustion which take place in the tissues. 



2 See " Moniteur Scientifique," du Dr. Quesneville. Aout et 

 novembre, 1872. 



