CHARACTER OF KATABOLISM 79 
any series of metabolism experiments to be subsequently applied to researches 
during muscular work. When the increment in the gaseous metabolism 
is as great as in experiments with severe muscular work, the method of 
employing an average base-line is open to the least objection. But in many 
researches in which an average base-line has been employed, the increment 
due to the superimposed factor does not amount to more than 20 per cent 
of the total metabolism; it can therefore readily be seen that the basal 
metabolism obtained as the average of a large number of figures cannot 
logically be used. It should be stated that in but relatively few experiments 
in this report was such an average base-line employed. 
An examination of the values for the respiratory quotient shows likewise 
a considerable fluctuation, ranging from 0.77 to 0.93, with an average value of 
0.85. As will be pointed out subsequently, the values for 0.77 were found on 
days following the ingestion of a diet poor in carbohydrates. 
The values of the pulse-rate have likewise been of interest inasmuch as 
they indicate the normal fluctuations that may be expected under the con- 
ditions of experimentation, ranging from 56 to 82 per minute, with an average 
of 63. On the other hand, values higher than 70 are recorded but twice, while 
values lower than 59 are recorded but three times. The respiration-rate ap- 
parently stayed remarkably constant throughout the whole period, fluctu- 
ating only from 17 to 24, and remaining almost constantly at 20 throughout 
the greater number of experiments. 
Having pointed out the futility of using a constant average base-line for 
metabolism experiments, particularly when relatively small increases in 
metabolism accompany the superimposed factor to be studied, it should be 
stated that many of the fluctuations here occurring may be easily interpreted 
by a reference to the statistical data accompanying the individual experi- 
ments. Noticeable alterations were observed in the carbon-dioxide produc- 
tion, the oxygen consumption, and the respiratory quotient. Each of these 
factors may readily be affected by extraneous conditions prior to the experi- 
ment, such as the general character of the diet, the degree of muscular activity 
on the day before, the storage of body-material, or the psychical stimulus 
which obviously was present in the first experiment. Furthermore, in a 
series of observations such as this, it is not unreasonable to look for the influ- 
ence of other less determined factors, such as cold weather, and the condition 
of training. 
In several instances a high metabolism was believed to have resulted 
from the greater muscular activity of the subject on his way to the laboratory, 
when he walked over a somewhat rough pathway, ran, or found it difficult 
to keep his balance owing to the icy pavements. The abnormality in the 
oxygen consumption during the early part of January may almost certainly 
be explained in large part by the condition of the streets at that time. 
The influence of training upon the metabolism is not easily estimated. 
The oxygen intake per minute per kilogram of body-weight remained remark- 
ably constant throughout the series of experiments, notwithstanding the fact 
that the subject gained 3.5 kilograms during the progress of the research. 
As this increase in weight took place while work was being constantly and 
steadily done, it was doubtless due in part to increased muscular develop- 
ment. On the other hand, the average intake of oxygen during the first 
