OFFICE OF EXPERIMENT STATIONS. 219 



by an experimental clay in which the diet was changed, while the 

 amount and character of the work remained the same. The short 

 series included one experiment of four days, in which the subject did 

 not work, followed b}^ an experimental day of rest and fasting. The 

 measurements of outgo of carbon, hydrogen, and energy were made 

 in two-hour periods, and the results will serve to show the relation 

 of elimination of these to the character and amount of work done. 

 The three fasting experiments throw some light upon the amount of 

 energy required for digestion. The general results of the experi- 

 ments are of unusual interest and importance. They attest the 

 validity of the statement previously made that these experiments go 

 a long way toward proving the application of the law of the conserva- 

 tion of energy in the living organism, if they may not be taken as 

 practically proving it. The results also appear to show a very slight 

 difference in the value of fat and sugar as a source of energy for mus- 

 cular work in favor of the sugar. 



In connection with this experimental work, 16 digestion experiments 

 have been made, 67 complete and 407 partial analyses of food and 

 excretory products were made, together with over 100 determinations 

 of heats of combustion of food materials and excretory products, by 

 use of the bomb calorimeter. 



Some new apparatus has been devised and changes and improvements 

 adopted which give increased efficiency. By means of a specially 

 devised thermometer for determining the internal body temperatures, 

 which has been in use the past year, temperature observations have 

 been secured which will constitute an important addition to the value 

 of the work done. 



At the request of the acting superintendent of the Elmira Reform- 

 atory, Elmira, N. Y., a study was made by some of our assistants 

 in Middletown of the dietaries of the inmates of that institution. 

 This study, while necessarily very limited in scope, gave results of 

 some value, and was of special interest as showing the possibilities 

 for such work and the need of investigation along this line. 



Under direction from Middletown, a study was made last year of 

 the dietaries of ten students at Harvard College by Mr. Edward Mal- 

 linckrodt, jr., with the cooperation of Professor Sanger. Some of 

 these students are obliged to live very economically and their food 

 consumption was quite limited. The studies were carried on during 

 three periods of three weeks each, one in the late fall, one in 

 winter, and one in late spring. Records of the physical condition of 

 the subjects were made during each experimental period. The data 

 of the investigation will, it is expected, serve as a valuable contri- 

 bution to the subject of the food consumption of sedentary persons. 

 The dietary and digestion experiments with members of the Harvard 

 boat crews at New London, begun last year, and carried out with the 

 cooperation of Dr. E. A. Darling, have been completed. 



Besides the investigations for this Department, several other lines 

 of nutrition investigations are carried on at Middletown under Pro- 

 fessor Atwater's supervision. 



The experiments referred to in my last report as being conducted 

 under the auspices of the committee of fifty for the investigation of 

 the drink problem have been completed. While this work is entirely 

 independent of the Department of Agriculture, still the material thus 

 gained will prove of much value in connection with the general nutri- 

 tion investigations. Indeed, the main results of the experiments are 

 independent of those relating to the action of alcohol. The investi- 



