CHARACTER OF KATABOLISM 87 
which the external muscular work was but 35 calories. Consequently, in 
table 93 the respiratory quotients determined during muscular activity are 
classified according to the accumulated amount of work done, the values 
secured before and after the work-period also being included. The work 
each morning was practically continuous; the table therefore shows the quo- 
tients obtained at various times during the morning as the amount of external 
muscular work gradually accumulated. 
The quotients given for the periods before work are usually the average 
of those obtained for two or three periods, and probably represent the true 
values, but those for the work-periods are individual determinations and hence 
are liable to the errors which may creep into the determination of both the 
carbon dioxide and the oxygen. While every precaution was taken to pre- 
vent error, it is pointed out that these individual values should be used with 
extreme caution, and deductions can only be drawn from the tabulated results 
as a whole. 
The respiratory quotients before work demand no particular discussion 
at this point, but the quotients obtained during work, and particularly the 
relationship to the amount of work done, indicate that as the experimental 
year progressed the amount of work increased until in the latter part of the 
year practically all of the experiments were made with excessive amounts of 
muscular activity. An examination of the data shows that in the majority 
of the experiments the quotients tend to increase as the total amount of 
work increases on any particular day. This is not invariably the case, as in 
several of the experiments there is a marked fall in the quotient during the 
second work-period. Considering only the experiments with M. A. M., 
we find that on 13 days the quotients decreased in value while on 18 days 
they increased. 
This tendency for the quotients to increase with the increased work has 
an important bearing upon the interpretation of the results. If, for example, 
the metabolism were of exactly the same character during muscular work 
as it was during the preceding rest-period, there would be a certain draft upon 
body-glycogen which, under the conditions of these experiments, namely, 
no food in the morning, would cause a rapid reduction in the storage of car- 
bohydrates. Under these conditions we should normally expect to find 
an invariable decrease in the respiratory quotient as the work progressed, as- 
suming that the character of the metabolism remains exactly that prior to 
the experiment. Since on the whole the results show an increase in the respira- 
tory quotient rather than a decrease, this evidence would point strongly to 
the fact that the character of the katabolism during the muscular work does 
not remain the same as that prior to the work, but that there was an increased 
combustion of carbohydrate. This is furthermore accentuated by the fact 
that in all but a very few experiments there was a marked drop in the respira- 
tory quotient during the period after the work was finished. This finding 
during the first hour after work is usually substantiated by observations 
made during the second hour, as well as in the relatively few instances in 
which the respiratory quotient was followed for several hours after work. 
These figures then, taken as a whole, indicate strongly that during the 
period of severe muscular activity the character of the katabolism is altered 
by an increase in the amount of carbohydrates burned, the storage of carbo- 
