396 BEPORT OF OFFICE OF EXPERIMENT STATIONS. 



fell bolow 10.5 {i;rams. Dotailod data arc also <;ivon rcfj^ardinj:^ the 

 variations in excretion of other urinary constituents. 



Marked variations in the amount of water vapor <;iven off hy the 

 skin and lun<;s were ob.served in exj)erinients with different subjects 

 and snudler variations in experiments with the same subject. On an 

 averajje, the results show that a fasting man gives off in this wa}' not 

 far from 600 to 800 giams of water per day. 



As the fasting period progressed a rather persistent decrease in the 

 carbon-dioxid output was noted. In the two-day fasting experi- 

 ments wide variations in the carbon-dioxid output were observed 

 with different subjects, though considering the period as a whole the 

 agreement was reasonably uniform. Much wider difl'erences were 

 noted between the oxygen intake on the different days than was the 

 case with the carbon-choxid output. 



The recorded data furnish information regarding the amounts of 

 protein, fat, and glycogen katabolized in the body. The results show 

 that the greatest draft on body glycogen occurretl on the first day of 

 fasting. After this a marked decrease in carbohydrate metabolism 

 was noted, and on the second, third, and subsequent days not far from 

 20 grams of glycogen per day was lost on an average. 



The average heat production in the fasting experiments was found 

 to be not far from 2,000 calories per day on the first two days of the 

 fasting period. When the experiments were continued longer the 

 heat production diminished, and the author believes that 1,500 to 

 1,600 calories per day may be considered as api)roximately the mini- 

 mum heat production of a man at rest without food. During sleep 

 the heat production of such a man falls to 56 calories per hour, or at 

 the rate of about 1,350 calories per day. 



The recover}- from fasting was rapid, and the author is of the 

 opinion that there is a marked tendency on the part of the bod}^ to 

 accumulate fat after short periods of fasting. 



An interesting bulletin on the influence of muscular and mental 

 work on metabolism and the efliciency of the human body as a 

 machine by Benedict and Carpenter " has been ])ublishe(l. Briefly, 

 mental work was not found to exercise any appreciable effect on the 

 factors of metabolism which were measured with the respiration 

 <^alorimeter. As regards the effectiveness of the body as a machine, 

 the authors calculate that it shows an efliciency of 20 per cent; that 

 is, for every calorie of muscular work produced by the body a total 

 of 5 calories is expended. 



The reports of the Carnegie Institution for the last two years contain 

 very interesting and valuable data regarding the installation and 

 equipment of the Nutrition Research Laboratory, at Boston, and 

 briefly report some of the work which has been accomplished. ^ 



a U. S. Dept. Agr., Office Expt. Stas. Bui. 208. 



b Carnegie Inst. Washington Year Book, 6 (1907), pp. 130, L'OO; 7 (1908), pp. 158, 209. 



