APPARATUS AND METHODS USED IN THIS RESEARCH. 55 

 METHOD OF DETERMINING THE DEGREE OF MUSCULAR REPOSE. 



The intimate relationship between minor muscular activity and 

 metabolism was soon recognized in experimenting with men in the 

 large respiration calorimeter at Wesley an University, Middletown, 

 Connecticut, and all of the earlier publications of researches with this 

 apparatus accentuate the importance of having a regular life routine 

 throughout the experimental period. The first attempt to secure such 

 regularity was the preparation of a program for each experiment, to 

 be rigidly adhered to by the subject. This was followed by a record, 

 made directly on the protocol sheets, of both the major and minor 

 muscular movements which were noted by the physical observer through 

 the window of the respiration calorimeter — a routine that was carried 

 out for a number of years in all of the experiments. 



In the later experiments made at the Nutrition Laboratory in Boston, 

 a pneumograph was placed about the chest of the subject, primarily to 

 record the respiration and the pulse-rate. These curves showed not only 

 the rise and fall of the chest in respiration, but also any other muscular 

 movements of the subject. This record was the first step towards a 

 graphic representation of muscular activity during metabolism experi- 

 ments, and played a very important part in an extensive research on dia- 

 betes 1 in comparing the metabolism of normal individuals and diabetics. 



APPARATUS USED IN THE RESPIRATION EXPERIMENTS. 



The success of this method of graphic registration in experiments on 

 man led to the development of a method for the registration of the 

 movements of animals. The first apparatus used in this laboratory 

 was that devised by Benedict and Homans, 2 in which one end of the cage 

 containing the animal was supported by a knife edge and the other 

 by a stout spiral spring; the slightest change in the center of gravity of 

 the animal changed the tension upon the spiral spring, causing the 

 suspended end of the cage to move up or down. By means of a rod 

 connected with the end of the cage and carried out through the top of 

 the chamber, the movements of the cage were traced directly upon a 

 kymograph. The mechanical difficulties of passing this rod through 

 the cover of the chamber, which must be air-tight, were overcome, but 

 later a tube pneumograph was substituted. This pneumograph was 

 attached to the cage and the wall of the chamber parallel to the spiral 

 supporting the free end of the cage. The slightest lengthening or 

 shortening of the pneumograph produced a change in the tension of 

 the confined air, these varying air tensions being transmitted by a tube 

 through the walls of the chamber to a delicate tambour and pointer 

 which gave graphic records on a kymograph drum. 



x For a reproduction of these curves, see Benedict and Joslin, Carnegie Inst. Wash. Pub. No. 

 136, 1910. 



2 Benedict and Homans, Am. Journ. Physiol., 1911, 28, p. 29. 



