AKIMAL HEAT. 4:03 



warmer than in the left ; while in horses, dogs, and probably 

 in man, where there is considerable loss of heat by the skin, 

 the blood is warmer on the left side. It is difficult to ex- 

 plain how the blood can pass through the lungs without 

 losing a certain amount of heat, but the experiments just 

 detailed, taken in connection with some of the earlier ob- 

 servations, leave little doubt as to the fact. 



These experiments are only indirectly applicable to the 

 human subject ; and if it be proven that in animals, the con- 

 ditions vary with " the state of the skin, the digestive appa- 

 ratus, and the muscular system," * it is impossible, in the 

 absence of positive demonstration, to say what change in 

 temperature, if any, takes place in the blood in its passage 

 through the lungs. The only reliable observations upon 

 this point in man are those lately made by Prof. Lombard, 

 of Boston. Prof. Lombard used in his experiments a very 

 ingenious and delicate thermo-electric apparatus, capable 

 of indicating a difference of -^-^ of a degree cent. 8 With 

 this instrument, he was able to determine very slight 

 variations in the temperature of the blood in the arterial 

 system, by simply placing the conductors over any of the 

 superficial vessels, like the radial. Of course it is impossible 

 to note the actual temperature in the two sides of the heart 

 in the human subject during life ; but Prof. Lombard en- 

 deavored to arrive at the same end, by calculating that if all 

 the sources of refrigeration in the lungs were artificially 

 removed, the blood in the arteries should gain about the 

 same amount of heat that would be lost under ordinary con- 

 ditions. To effect this object, he breathed air saturated 

 with moisture and of the same temperature as the circulating 

 blood. " If, then, when respiration takes place under ordi- 

 nary circumstances, the blood is cooled one-third of a degree 

 (cent.) in passing through the lungs, the temperature should 



1 COLIN, loc. tit. 



2 LOMBARD, Description d'un nouvel appareil thermo-electrique pour P etude de 

 la chaleur animale. Archives de physiologic, Paris, 1868, tome i., p. 498. 



