858 METABOLISM. 



dogS by HlRSCHFELD, KUMAGAWA, KLEMPERER, MUNK, ROSENHEIM, 1 



and others. It follows from these experiments that the lower limit of 

 protein needed for human beings, for a week or less, is about 30^0 grams 

 or 0.4-0.6 gram per kilo with a body of average weight, v. NOORDEN 2 

 considers 0.6 gram protein (absorbed protein) per kilo and per day as the 

 lower limit. The above-mentioned figures are valid only for short series 

 of experiments; still there exists the observation of E. VOIT and CON- 

 STANTINIDI 3 on the diet of a vegetarian when the protein condition was 

 kept almost but not completely normal for a long time with about 0.6 

 gram of protein per kilo. CASPARI 4 has also made observations upon a 

 vegetarian for a period of 14 days with an average of 0.1 gram nitrogen 

 (recalculated as equal to 0.62 gram protein) per kilo, where a nearly com- 

 plete nitrogenous equilibrium was observed as the average result. 



According to VOIT'S normal figures, which will be spoken of below, for 

 the nutritive need of man, an average workingman of about 70 kilos 

 weight, requires on a mixed diet about 40 calories per kilo (true calories 

 or net calories). In the above experiments with food very poor in pro- 

 tein the demand for calories was considerably greater; as, for instance, 

 in certain cases it was 51 (KUMAGAWA) or even 78.5 calories (KLEMPERER). 

 It therefore seems as if the above very low supply of protein was pos- 

 sible only with great waste of non-nitrogenous food ; but in opposition to 

 this it must be recalled that in VOIT and CONST ANTINIDI'S experiments 

 upon the vegetarian, who for years was accustomed to a food poor 

 in protein and rich in carbohydrate, the calories amounted to only 43.7 

 per kilo. In the case studied by CASPARI a supply of 41 calories per kilo 

 was entirety sufficient. 



SIVEN has shown by experiments upon himself that the adult human 

 organism, at least for a short time, can be maintained in nitrogenous 

 equilibrium with a specially low supply of nitrogen without increasing 

 the calories in the food above the normal. With a supply of 41-43 calories 

 per kilo he remained in nitrogenous equilibrium for four days with a supply 

 of nitrogen of 0.08 gram per kilo of body weight . Of the nitrogen taken, 

 a part was of a non-protein nature and the quantity of true protein nitro- 

 gen was only 0.045 gram, corresponding to about 0.3 gram of protein per 

 kilo of body weight. That this low limit, which by the way holds only 

 for a short time, has no general validity follows from other observations. 

 Thus CASPARI 5 also, in an experiment on himself, could not attain com- 



1 See footnote 3, page 846; also Munk, Arch. f. (Anat. u.) PhysioL, 1891 and 1896; 

 Rosenheim, ibid., 1891; Pfliiger's Arch., 54. 



2 Grundriss einer Methodik der Stoff wechseluntersuchungen. Berlin, 1892. 



3 Zeitschr. f . Biologe, 25. 



4 Physiologische Studien iiber Vegetarismus, Bonn, 1905. 



B Siven, Skand. Arch. f. PhysioL, 10 and 11; Caspari, Arch. f. (Anat. u.) PhysioL, 

 1901. 



