Sugar and Oxygen Relationships in Blood. 121 



dog similar in all respects save that the exercise factor was elimi- 

 nated. The figures given in the table are the averages of the 

 data obtained from five dogs. 



The fact that the averages of the initial samples are so nearly 

 identical for each constituent, indicates that our series is sufficiently 

 long to permit the attaching of significance to subsequent varia- 

 tions. 



Since it is desirable to compare figures which were obtained 

 under conditions identical except for the added element of exercise, 

 we wish to point out that in studying the table the figures given 

 for exercise should be compared with the figures for the corre- 

 sponding periods of rest, rather than with the initial values for 

 the exercise experiments. This is indeed necessary in the inter- 

 pretation of the effect of work because variations of significant 

 magnitude in the control series make comparisons between initial 

 and successive periods unjustifiable for this purpose. 





Experi- 



Number of 



Elapsed Time in Hours. 





mental 



Experiments 













Conditions. 



Performed. 



0. 



2. 



4- 



6. 



Oxygen content c.c. per 100 c.c. 

















Rest 



12 



16.5 



13.7 



14.5 



14.0 





Work 



13 



I6.I 



17.3 



17.0 



16.6 









-0.4 



+3-6 



+2.5 



+ 2.6 



Oxygen capacity c.c. per 100 c.c. 

















Rest 



12 



24.6 



23.8 



23.6 



23.1 





Work 



13 



24.8 



25.6 



26.4 



26.4 









+0.2 



+ 1.8 



+2.8 



+3-3 



Volume of corpuscles expressed 















Rest 



8 



49.9 



47-1 



46.9 



47-9 





Work 



10 



49-i 



50.6 



51.0 



51.5 









-0.8 



+3-5 



+4-1 



+3-6 



Sugar as glucose mg. per 100 c.c. 

















Rest 



12 



69 



68 



70 



66 





Work 



13 



69 



66 



64 



60 









0 



— 2 



-6 



-6 



From the table it will be seen that the oxygen content of the 

 blood rises during the first period of work as compared with the 

 first period of rest and falls slightly thereafter. These results 

 may be due among other things, to increased aeration in the 

 lungs, increased oxygen capacity of the blood, and to an increased 

 rate of blood flow through the tissues. 



The oxygen capacity of the blood rises progressively, but at a 

 decreasing rate, throughout the period of work. This phenomenon 



