A HISTORY OF METABOLISM 77 



several balloon ascensions for scientific purposes. He also measured the 

 cost of energy at which horses and cattle performed work, and the loss of 

 energy through the bacterial putrefaction of the foods in such herbivora. 

 Magnus-Levy, a pupil, carried the Zuntz respiration apparatus to the 

 1 rdside of hospital patients and made pioneer investigations the validity 

 of which has been generally confirmed. Zuntz had a quiet, attractive 

 personality, without, however, possessing the breadth of view of Rubuer, 

 who was the ino-st frequent antagonist of his views. 



Late French Work 



If we turn back to France for a moment, which we left in the year 

 1819, we find an important paper by Berthelot (1827-1907) entitled "Sur 

 hi chaleur anirnale," published in 1865, in which he argues concerning the 

 differences in the quantities of heat produced when equal weights of 

 carbohydrate and fat are oxidized in the body. He points out that it is 

 impossible to determine the heat production in the body by means of the 

 method of Lavoisier because 44 'gm. of carbon dioxid produced from the 

 oxidation of carbon yield 94 calories, whereas the same amount produced 

 from methane yields 210,000 calories. He thus early concludes that *the 

 quantity of heat liberated in the incomplete oxidation of a substance is 

 equal to the difference between the total caloric value of the substance and 

 that of the products formed." 



Rubner's calorimetric observations were the realization of this theo- 

 retical conception. 



The experiments of Charles Richet (1S50-. .), published in 1885, con- 

 firmed rtubner's Law of Surface Area, and Richet affirms that in future 

 one should express all calorimetric observations in terms of surface 

 area and not in weight, a principle now being largely followed in the 

 United States. Michet compared the heat production, as measured by his 

 ealoriftieter, of a eat, rabbit and goose of equal weights, as follows: 



Calories 



Weight per kilogram 

 , in grams per hour 



Cat ... 3135 3.30 



Rabbit 3100 3.32 



Goose 3310 3.32 



Writing, abewrt this work, in 1889, he says: "Let us consider a horse, 

 for example, winch weighs 525 kg. and having a radius, one may assume, 

 of 50 \centime*ers, the surface area would then be 31.5 square meters. 

 This at;ea is the same as that of 2250 sparrows, each weighing 20 grams.. 

 Consequently, sparrows weighing 45 kilograms have the same surface as a 

 horse weighing 523 kilograms." 



