August 20, 1009] 



SCIENCE 



251 



of quantitative changes in the total amount of 

 nitrogen eliminated." The fact that the amount 

 of creatinine excreted in the urine by a normal 

 individual is quite independent of the amount of 

 protein in the food, or of the total nitrogen in 

 tlie urine, has been verified by many investigators. 

 On the other hand, it seems to me that it is still 

 a question as to whether or not the absolute quan- 

 tity of creatinine eliminated even on a meat-free 

 diet is a constant quantity for the same indi- 

 vidual. Examination of Folin's results shows 

 that between the minimum and maximum creati- 

 nine values for the same individual of a group of 

 six normal men, during a period of five days, there 

 are differences of 0.09 to 0.2S gram of creatinine 

 per 24 hours, which differences amount to 6.4 to 

 22.9, the average being 13.32 per cent, of the 

 minimum creatinine values. Again, for a group 

 01 six normal men during periods ranging from 

 9 to IG days there are differences of 0.17 to 0.45 

 gram of creatinine per 24 hours, which differ- 

 ences amount to 15.6 to 35.5, the average being 

 21.0 per cent, of the minimum creatinine values. 

 Shaffer for two individuals during periods of 8 to 

 25 days found differences of 0.24 and 0.37 gram 

 of ci'eatinine per day, which equals 19.8 and 26.6 

 per cent, of the minimum creatinine values. These 

 variations, it seems to me, can not be considered 

 insignificant. 



The individual variations in the creatinine for 

 the 24 subjects of this investigation, upon a diet 

 containing meat, during a period of 220 days 

 range from 0.50 to 0.99 grams per 24 hours, 

 which equals 30.1 to 73.8 per cent, of the mini- 

 mum creatinine values. These variations are ap- 

 parently caused in the main at least by variations 

 in atmospheric temperature; as a rule, other con- 

 ditions being tlie same, the lower the temperature 

 the smaller is the excretion of creatinine, and vice 

 versa. The author is indebted to Professor A. P. 

 Mathews, of Chicago University, for valuable sug- 

 gestions in connection with this work. 



A Study of the Food Requirements of a Group of 

 Twenty-four Men: H. S. Grixdlet and H. H. 

 Mitchell. 



The detailed food requirements of a group of 

 24 men in apparently normal health, varying be- 

 tween 18 to 31 years of age and ranging between 

 54.0 and 80.1 kilograms in weight were accurately 

 determined for a period of 220 days. A proper 

 variety in diet, and, at the same time, a reason- 

 able regularity in protein, carbohydrate and fat 

 intake were secured by employing a carefully 

 arranged eight-day menu. The protein actually 



consumed per individual varied from 67 to 99, the 

 average for the 24 subjects being 85 grams per 

 man per day. The grams of protein per kilogram 

 of body weight varied from 1.11 to 1.44, the aver- 

 age for the 24 men being 1.28. 



The maximum protein value of 99 grams ob- 

 tained in this investigation is somewhat below the 

 so-called Voit and Atwater standards of 100 grams 

 for people doing light muscular work, but the 

 average value of 85 grams is decidedly above any 

 of the so-called minimum values of Chittenden, 

 while the minimum value of 67 grams which is 

 for a very light man weighing only 56 kilograms 

 or 123 pounds compares closely with Chittenden's 

 minimum values of 63 to 67 grams for men weigh- 

 ing upon an average 70 kilograms or 154 pounds. 



The fuel value varied per individual from 2,584 

 to 3,685, the average for the entire group being 

 3,135 calories per day. The calories per kilogram 

 of body weight ranged from 41 to 54, the average 

 being 47. The carbohydrates actually consumed 

 varied from 315 to 441, the average being 380 

 grams per man per day. The fat eaten varied 

 from 94 to 192, the average being 131 grams per 

 man per day. 



Composition of the Fat of Beef Animals on Dif- 

 ferent Planes of Nutrition (first paper) : C. 



R. MouLTON and P. F. Teowbeidge. 



Fifteen to twenty fat samples from each of nine 

 steers were investigated for moisture, fat and 

 protein content, iodine value, saponification value 

 and melting point. In the fatty tissue a high per 

 cent, of fat is accompanied by a low per cent, of 

 moisture and protein. The fat in the fatty tissue 

 increases with fatness, the moisture with leanness. 

 The fat per cent, in the fatty tissue increases from 

 outside to inside while the moisture decreases. 

 The iodine value of the fat increases with age, 

 fatness and distance from the inside of the body, 

 while the melting point falls. 

 Changes in the Com position of the Skeleton of 



Beef Animals (first paper) : P. F. Tbowbbidge 



and F. W. Woodman. 



Seven steers were selected, all of nearly the 

 same age and breed. They were fed to a good fat 

 condition and one was killed as a check (when 

 one year old). The others were put on the same 

 rations (corn chop, linseed meal and alfalfa), 

 varying in quantity so that two of the animals 

 were on submaintenance, losing one half pound 

 in weight daily. Two on maintenance and two on 

 supermaintenance, gaining one half pound daily. 

 One of each group was .slaughtered after six 

 months, the second submaintenance after eleven 



