. 568 JOHIST E. MUKLHST 



there is every reason to think that direct determinations of the total metab- 

 olism will be preferred to the indirect in many cases, and all classes of 

 animals, as it is undoubtedly preferable theoretically." Lefevre(^) says, 

 "Aussi bien la calorimetrie physique est a la base de toute recherche de 

 calorimetrie biologique." And Rubner(/>) points out that "Die urpriing- 

 liche Auffassung des Tierlebens als eine Verbrennung unter oxydativen 

 Abbau der Sto-ife hat der allgemeine energetischen weichen miissen, denn 

 die letztere umfasst auch jene primativen Lebensformeln bei Bakterien und 

 Hefe wo Spalttmgsvorgange ohne Beteiligung des Sauerstoffs die Quelle 

 der Energie fiir die Jebende Substanz bilden." Rubner also draws atten- 

 tion to the fact that in all organisms there are fermentative reactions not 

 directly related to the needs of the living substance, which nevertheless lead 

 to the development of heat. Such heat would represent pure loss of energy 

 unless, as in the higher animals which possess a specific chemical regula- 

 tion, it were turned to account in the maintenance of the body temperature. 

 The different fermentative processes therefore come within the field of 

 calorimetrie investigation. The production of living substance in the 

 growing organism on the other hand is of the nature of fermentative 

 changes which themselves involve no storage or liberation of energy, and 

 yet they are dependent upon energy changes and indeed may to a degree 

 be measured by the intensity of the oxidative capacity of the organism. 



Calorimetry as related to living organisms has two distinct fields: (1) 

 the physical measurement of the energy stored in the animal tissues and 

 in all chemical compounds which may serve the animal as food, likewise 

 the energy residual in the excretory substances rejected by the cells; (2) 

 the measurement of the energy set free as heat during the life processes. 



L The Heat of Combustion 



The unit of heat which has been employed for nearly a century is the 

 Calorie of Regnault, i. e., the amount of heat necessary to raise 1 kilogram 

 of water from to 1 C. This is the kilo-calorie written with a capital 

 C. The small calorie written "cal," called also the gram-calorie, i& the 

 amount of heat necessary to raise 1 gram of water from to 1 C. The 

 calorie more commonly used to-day is somewhat smaller than this, namely, 

 the amount necessary to raise a kilogram of water from 15 to 16 C or 

 from 19 to 20 C. In terms' of the original Regnault calorie the value 

 of the calorie at higher temperatures is given by Longuinine as follows : 



18 = 0.9995 

 20 = 0.99925 

 22 0.99915 

 25 = 0.99930 



