PHYSIOLOGICAL EFFECTS 165 
ing-period, but points out that this holds true only when the work is done 
easily and without fatigue. Under conditions of fatigue, he mainta i ns that 
the consumption of oxygen during the whole after-period following work may 
amount to the total oxygen consumption during 2 or 3 minutes of the work- 
period, and concludes that the high values found by Speck were due to 
fatiguing work. 
In experimenting on dogs, Porges and Pribram a studied the gas-exchange 
following the cessation of work. After citing the after-effects of work on 
metabolism as found by Speck, Katzenstein, Loewy, Lehmann and Zuntz, 
Zuntz and Schumburg, Zuntz, Loewy, Muller and Caspari with men, and 
Zuntz and Lehmann as well as Zuntz and Hagemann with horses, they report 
the results secured with their dog and attempt to explain the increased metab- 
olism on the basis of an increased ventilation of the lungs, assuming that each 
liter of lung ventilation requires an increase of 5 to 10 c.c. in the oxygen con- 
sumption. The authors computed the increase in the oxygen consumption 
incidental to the increase in the ventilation above the normal, and deducting 
this from the values actually found, they state that the total increase found 
with their animal corrected for the increase in the lung ventilation did not 
continue over 1 hour. Inasmuch as they were using a tracheotomized dog, 
which under conditions of work necessitated an artificial control of the tem- 
perature, it is obvious that these experiments were not best adapted for study- 
ing the after-effect of work. Undoubtedly there were temperature disturbances 
which even the artificial method for cooling the animal could not entirely 
prevent. 
The question of the after-effects of muscular work upon metabolism is 
much more than simply an interesting physiological problem, since it has an 
important bearing upon the technique of studying metabolism in the higher 
mountains. Jaquet b maintains that there is a considerable after-effect 
of work and believes that until at least 24 hours has elapsed after reaching 
the high altitude, the subject is not in condition to be examined for the influ- 
ence of high climate upon metabolism. Hence he recommends that localities 
should be selected for this kind of research to which the subjects can be 
carried by a mountain railway, thus eliminating the intense fatigue and ex- 
cessive muscular strain incidental to climbing with baggage and apparatus 
to the point selected for the study. It is obvious that in studies of the influ- 
ence of muscular work on the metabolism, there would be the least objection 
to the after-effects of the exercise of climbing inasmuch as usually large energy 
transformations are considered; on the other hand when a study is made of 
the influence of high altitude per se upon normal resting metabolism, it is a 
serious question as to whether or no the after-effects of muscular work are 
not such as to vitiate the results of many of the experiments made on this 
important point. 
To secure definite evidence with regard to the after-effects of work upon 
metabolism, a large number of experiments were made in connection with this 
research in which the metabolism in the period following the severe muscular 
work was studied. The results of these studies have been brought together 
in table 136, in which are given the metabolism before the work began, the 
■ Porges and Pribram, Biochem. Zeitsch., 1907, 3, p. 453. 
& Jaquet, Archiv f. exp. Path. u. Pharm., 1910, 62, p. 341. 
