METHODS AND APPARATUS 23 
resting metabolism was determined on a great many days, the evidence se- 
cured supplies a basis for comparison as to the constancy of values obtained 
under these conditions as well as evidence regarding the normal drafts upon 
the body-material when the subject was lying quietly without food and awake. 
From the respiratory quotient the character of the material burned, and there- 
fore the character of the draft upon the body-material can be approximately 
computed. Furthermore, the base-line with regard to the measurement of the 
total metabolism under these conditions can be quite definitely established. 
Experience in this laboratory has shown that there is a marked difference 
between the metabolism when the subjects are sound asleep and when they 
are awake, even though they are well trained and capable of the greatest 
muscular relaxation. It can be seen, therefore, that our base-line determined 
in the morning without breakfast is by no means the minimum metabolism 
of the subject, but represents the minimum metabolism when awake. On 
purely theoretical grounds it might have been of value to obtain the minimum 
metabolism of the subject when sound asleep, but this was impracticable. 
It is perhaps needless to state that during the course of the winter the subject 
became extremely automatic in his relations to the experiments, and hence 
if there was any evidence regarding the value of training for an experiment or 
of training to decrease the incidental muscular activity which might be volun- 
tarily controlled, we should expect to find it here. As a matter of fact, from 
the very start the subject was not affected in any way, psychologically or 
otherwise, by the simple routine of the experiments, and we have every reason 
to believe that the minimum metabolism when the subject was awake was 
accurately determined. 
Since the minimum metabolism under these conditions does not represent 
the true minimum metabolism of the subject, and since such a base-line is 
arbitrarily taken for purposes of comparison, it seemed advisable to secure 
data with regard to base-lines under other conditions. For example, the sub- 
ject when riding must sit upright on the seat of the bicycle ergometer with the 
feet on the pedals. Inasmuch as this calls for an increase in the metabolism 
above that of lying quietly, exactly as lying awake calls for an increased me- 
tabolism over lying quietly asleep, it seemed logical likewise to determine the 
metabolism in the sitting position. This was done in a number of instances. 
Again, the legs must move in rotating the wheel, and experiments were made 
,in which, by belting a motor to the rear wheel of the ergometer, it was possible 
to drive the ergometer and thus rotate the legs of the subject at the various 
speeds employed in the regular work experiments. The values obtained 
under such circumstances would obviously form still another base-line. 
Then again, as the subject must in rotating the wheel overcome the ordinary 
small friction of the machine, a series of experiments was made in which the 
subject simply rotated the pedals by riding without load. Furthermore, the 
load was varied so that a series of experiments was carried out with a very 
low load and increased step by step to the maximum load. Each of these 
different values can all logically be taken as a series of base-lines for compar- 
ison with the highest loads, and thus afford the greatest possibility for varia- 
tions in the subsequent comparisons. 
Finally, since there is much contradictory evidence regarding the after- 
effect of muscular work on metabolism, a number of experiments were con- 
