876 METABOLISM. 



of climate, it is not remarkable that a person accustomed to a mixed 

 diet can exist for some time on a strictly vegetable diet deficient in pro- 

 teins. No one doubts the ability of man to adapt himself to a heteroge- 

 neously composed diet when this is not too difficult of digestion and is 

 sufficient in quantity; nor can we deny that it is possible for a man 

 to exist for a long time with smaller amounts of protein than VOIT 

 suggests, namely 118 grams. Thus O. NEUMANN l experimented on him- 

 self during 764 days in three series of experiments, and his diet consisted 

 of 7.42 grams protein, 117 grams fat, and 213 grams carbohydrates =2367 

 gross calories, with a weight of 70 kilos and with ordinary laboratory 

 work. These figures cannot be compared with those obtained by VOIT'S 

 worker, weighing 70 kilos, whose work was harder than a tailor's and 

 easier than a blacksmith's; for example, the work of a mason, carpenter, 

 or cabinet-maker. The very extensive investigations recently performed by 

 CniTTENDEN 2 on the determination of the extent of protein necessary are 

 of great interest. These investigations, upon a total of twenty-six persons, 

 extended over a period of five to twenty-months, and consisted of careful 

 observations upon the manner of living, food taken, nitrogen elimina- 

 tion, and the ability of performing work. The individuals were divided 

 into three groups. The first consisted of five professional men (four 

 assistants and one professor). The second group was composed of 

 thirteen soldiers (of the sanitary corps of the United States army) who 

 besides their daily work were given gymnastic exercises for six months. 

 The third group consisted of eight athletic students who were trained in 

 different kinds of sport. 



In all the persons experimented upon the original nitrogen content 

 of the food, which corresponded to VOIT'S value or were somewhat higher, 

 was gradually reduced more or less. The total calories supplied were 

 not increased above the original value, but rather diminished to a reason- 

 able extent. The bodily as well as the mental ability was repeatedly 

 tested. As it is not possible to enter into the details of the investiga- 

 tion the following will be sufficient to show the results. With a diet 

 corresponding to VOIT'S values the amount of urine nitrogen per day is 

 16 grams, corresponding to a total protein catabolism in the body of 100 

 grams or 1.43 grams per kilo. The corresponding results for the above 

 three groups may be found in the following table, where for comparison 

 HAMMARSTEN also includes the figures for VOIT'S diet: 



1 Arch, f . Hygiene, 45. 



2 R. H. Chittenden, Physiological Economy in Nutrtition, New York, 1904. 



