HEAT REGULATION. 871 



a rise in the metabolism; the conditions on lowering the external tem- 

 perature are rather more complicated, and a chemical heat regula- 

 tion in the strict sense is difficult of exclusion, especially in small animals. 

 If the natural muscular activity is eliminated by poisoning with curare 

 or by section of the spinal cord, then, as shown by PFLUGER l and his 

 pupils, the warm-blooded animal behaves like a cold-blooded animal, 

 and the metabolism decreases parallel with the body temperature. In 

 normal animals, on the contrary, the body temperature can be kept 

 constant, on lowering the external temperature, by an increased met- 

 abolism. On sufficiently cooling the body the temperature sinks 

 irrespective of the increased metabolism, and at a certain limit of tem- 

 perature the catabolism of substance is still lower with decreasing tem- 

 perature. 



A very interesting and important question is the action of high altitude 

 upon the oxidation processes, the economy of temperature, the protein 

 exchange and the general metabolism. The results of the laborious 

 and important investigations on this subject may be found in the large 

 work of N. ZUNTZ, A. LOEWY, F. MULLER and W. CASPARi. 2 



That the ingestion of food raises the metabolism has been known for 

 a rather long time, and this has been studied by ZUNTZ, v. MERING, MAG- 

 NUS-LEVY, VOIT, RUBNER, JOHANSSON and collaborators and also by 

 HEiL-NER. 3 It follows from these investigations that this rise in metabo- 

 lism, which in man, on sufficient supply of food, amounts to a rise of 10-15 

 per cent of the basal requirement and with abundant supply of 

 food may be still larger (35 per cent in the researches of JOHANSSON, 

 TIGERSTEDT and collaborators), has a double cause, namelv, partly a 

 digestion work (ZUNTZ) and partly a chemical decomposition (specific 

 dynamic action of RUBNER) which takes place at the same time. 



The sum of all the work which is necessary for the chemical trans- 

 formation of the foods, as well as for the mechanical division and trans- 

 portation of the food in the intestinal canal, is called the digestion work by 

 ZUNTZ. That such work exists has been shown by ZUNTZ and v. MERING 

 by comparative tests of the different action upon metabolism by foods 

 introduced per os and intravenously, and recently COHNHEIM 4 has shown 

 that in sham feeding an increased catabolism of non-nitrogenous body 



1 See footnote 2, page 562. 



2 Hohenklima und Bergwanderungen in ihrer Wirkung auf den Menschen, Berlin, 

 1906. 



3 Zuntz and v. Mering, Pfliiger's Arch., 15: Zuntz, Naturw. Rundschau. 21 (1906), 

 with Hagemann, 1. c., with Magnus-Levy, Pfliiger's Arch., 49; Magnus-Levy, ibid.*. 

 55. and v. Noorden's Handbuch; Voit, Hermann's Handbuch, 6; Rubner, Zeitschr. 

 f. BioL, 19 and 21, and Arch. f. Hyg., 66; Johansson, Skand. Arch. f. Physiol., 21,. 

 with Koraen, ibid., 13; Heilner, Zeitschr. f. Biol., 48 and 50. 



4 Arch. f. Hyg., 57. 



