88 



RESPIRATION 



gas determination mentioned in Chapter IV. Warned by previous 

 failures of physiologists to recognize the exactitude of normal 

 physiological regulations, we used defibrinated human blood, of 

 which fresh samples could be obtained at any time from the same 

 individual under normal conditions. At the outset we wasted much 

 time, however, through failing to realize that it was necessary to 

 have the blood fresh for each experiment, as blood outside the 

 body undergoes slow changes which diminish its capacity for 

 carrying CO 2 . 



Figure 25 shows the results obtained with my own blood. 



Figure 25. 



Lower curve absorption of CO2 by blood of J. S. H. in presence of air and C(>2. 

 Upper curve absorption of CC>2 by blood of J. S. H. in presence of hydrogen and 

 C0 2 . 



Attention may first be directed to the lower curve, showing the 

 amounts of CO 2 taken up in the presence of air and varying pres- 

 sures of CO 2 . The first, and by far the most striking, point to be 

 noted is that, although the different determinations were made on 

 different days covering a period of about six months, they all lie 

 on one curve. The samples were taken at different times of the day 



