

INVESTIGATIONS ON METABOLISM. 97 

DAILY ROUTINE OF THE EXPERIMENTS. 
The digestion experiment which was made with each respi- 
ration experiment commenced two or three days before the 
latter, but both ended at the same time. On the second or 
third day of the digestion experiment the subject entered the 
respiration chamber, but, in order to insure normal conditions, 
the respiration experiment did not begin until six hours after 
he had entered. This allowed the man an opportunity for 
arranging his furniture, the hygrometer, thermometer, and 
other apparatus in the room, and permitted the establishment 
of the needed equilibrium of temperature and moisture content 
in the chamber preparatory to the respiration experiment itself. 
The occupants of the chamber passed the time in such, ways 
as were in general most agreeable under the circumstances. 
They observed regular hours of eating and sleeping. There 
was, of course, almost no opportunity for exercise. In the last 
experiment, however, a special arrangement was made for 
vigorous muscular labor in lifting and lowering a weight sus- 
pended from a pulley. Abundant opportunity was given for 
reading, considerable conversation was held between the occu- 
pant and the men who did the work outside, and the monotony 
was also relieved from time to time by visitors. 
The amount of labor involved in these experiments is very 
considerable. [he work goes on day and night. Relays for 
day and night work were, of course, necessary. During the 
day a force of five or six persons was generally employed. 
During the night, when the occupant of the chamber was 
asleep, the force was reduced to three. 
A brief description of the routine of one day will perhaps 
help to a better understanding of the way in which the experi- 
ment is carried out. ‘The night force of operators was relieved 
at seven o’clock a.m. At that time the subject.was awake 
and ready for breakfast. The assistant, who had charge of the 
preparation and cooking of the food, prepared the breakfast; 
the chemist of the night force changed the system of U tubes 
for analysis of the air. ‘The day chemist proceeded to start the 
passage of the air through the fresh system of tubes, and then 
weighed the system which had just been removed; the read- 
ings of the meter, by which the ventilating current of air was 
measured, and of temperature, barometric pressure, etc., were 
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