48 Dr. W. Marcet. The Influence of Exercise [June 8, 



nearly twice the amount expired in a perfect state of repose (213*3 c.c. 

 and 434*1 c.c.); the mean excess, 221*7, may be looked upon as due to 

 the production of heat to be converted into motion, but it will be 

 seen presently that there is really more heat developed from carbon 

 burnt to the extent of about 12 per cent, of the above excess. The 

 oxygen absorbed, 65*4 c.c., looks much too high, as the mean amount 

 obtained under the influence of food in my last experiments is 35' 7, 

 and at first it occurred to me that more oxygen was really absorbed 

 under exercise than in repose. But on inquiring closely into the 

 present result, it became obvious that this figure for oxygen absorbed 

 included some oxygen retained in the body as C0 2 . The next point 

 was to determine, if possible, how much oxygen was absorbed for 

 tissue-change, and how much was retained as C0 2 . This result was 

 obtained by a consideration of the third stage of the experiment 

 which concerned resting after exercise. In this third stage the mean 

 excess of C0 2 found to have been expired under exercise over the 

 C0 2 expired in repose is equal to 500 c.c. for a mean exercise of 

 18 mins. 31 sees. ; or, in other words, in 18 mins. 31 sees, an amount 

 of C0 2 had accumulated in the body equal to 500 c.c. Assuming that 

 this accumulation took place regularly, it would have amounted to a 

 mean of 27*6 c.c. per minute. We are now in a position to find out 

 the volume of CO 2 present, together with the amount of O absorbed 

 per minute ; this is done by subtracting the volume of C0 2 absorbed 

 per minute, or 27'4 from the volume of O entered as absorbed, or 

 65*4 ; this gives 38 c.c. for the actual volume of oxygen absorbed, 

 which is very near to the figure 35*7, the mean volume of oxygen 

 absorbed in my case under food ano! in the state of repose. 



It then occurred to me that the total C0 2 retained in the blood 

 under exercise might bear some proportion to the excess of C0 2 

 expired under exercise over the C0 2 expired sitting. On calculating 

 these relations I found that there certainly was such a ratio. Of 

 course the ratio varied somewhat in each experiment, but the means 

 of the ten experiments gave the figure 0*123, while the extremes were 

 0*110 and 0*140. Therefore, by multiplying the mean ratio 0*123 by 

 the excess of the C0 2 under exercise over the C0 2 in repose, the result 

 will give, with a certain degree of approximation, the figure for the 

 CO 2 absorbed per minute during the exercise without being at the 

 trouble of determining this figure experimentally. 



We now turn to the corresponding experiments made on Mr. Davis. 

 There are five of them ; the sixth was discarded from some irregu- 

 larity which could not be accounted for. 



In the first experiment the air expired was collected on beginning 

 the exercise ; in the second it was collected six minutes after exer- 

 cise was begun ; in the third 9 mins. after ; in the fourth 12 mins. ; 

 and in the fifth 15 mins. after. 



