24 MUSCULAR WORK 
tinued after the work-periods ceased. Under these conditions the carbon- 
dioxide production and oxygen consumption were both measured, and care- 
ful records of the pulse-rate made. In a few experiments a record of the 
respiration was likewise made by means of the spirometer attached to the 
ordinary form of respiration apparatus, so as to obtain data regarding the 
respiratory types before and after work, but for reasons given subsequently 
it was impracticable to use the spirometer during the muscular-work periods. 
DETERMINATION OF THE NITROGEN EXCRETION. 
It was hoped that a reasonably careful study of the urine during severe 
muscular work could be made, although evidence in the earlier literature with 
regard to the nitrogen excretion is much more abundant than that with regard 
to the gaseous exchange. Unfortunately, while the subject was most tractable 
and cooperated in every way with the investigation while inside the laboratory, 
it was very difficult to control the diet outside and even more difficult to 
insure a proper collection of the urine and feces; hence we soon had to give 
up the plan of securing 24-hour specimens of urine for comparison purposes. 
When possible, however, the subject emptied the bladder before the experi- 
ment began and again after it was over. The data secured have been collected 
and will be subsequently discussed, but they give only fragmentary evidence 
with regard to the nitrogen excretion as affected by severe muscular work. 
PULSE OBSERVATIONS. 
The intimate relationship between the pulse-rate and the metabolism 
so regularly noticed in this laboratory led to an attempt to secure the pulse- 
rate during these experiments. When the subject was lying quietly upon the 
couch,' the observations were made with the greatest fidelity and regularity 
and became an integral part of each individual period. When the subject 
was riding on the ergometer, it was very difficult to secure accurate records 
of the pulse-rate, although attempts were made to obtain these by means of 
the stethoscope and occasionally from the radial pulse. While observations 
were made in practically every experiment, they were by no means so frequent 
as we should have liked, and obviously some other form of technique will 
be essential for studying satisfactorily the pulse-rate under these conditions. 
At the time the experiments were made, we had no string galvanometer or 
oscillograph at our disposal for securing such records. 
DETERMINATION OF THE ALVEOLAR AIR 
The marked changes in the respiratory quotient noted in many experi- 
ments led to observations on the alveolar air, and the influence of muscular 
work upon its composition. These determinations were made through the 
assistance of Mr. H. L. Higgins of the laboratory staff, and were carried out 
by the Haldane ° method, the sample being analyzed by means of the small 
Haldane gas-analysis apparatus. 6 
OBSERVATIONS ON THE INFLUENCE OF DIET. 
The difficulties incidental to an adequate control of the subject while 
outside the laboratory and his disinclination to follow rigidly a diet, even 
a Haldane and Priestley, Journ. Physiol., 1905, 32, p. 225. & Haldane, Methods of air analysis, London, 1912. 
