376 INFLUENCE OF CONTRACTING MUSCLE ON THE BLOOD. [BOOK I, 



muscle in repose. It may be brighter even when the blood contains 

 less oxygen. 



2. Blood streams more rapidly out of contracting, than out of 

 resting, muscle. 



3. Taking arterial blood as the standard, the following table 

 represents the condition of venous blood from resting and from 

 active muscle. 



Since blood streams more rapidly from active muscle than from 

 muscle at rest, these differences of the blood in the two cases are 

 really much more considerable than the table shews; since in a given 

 interval of time more blood, with its reduced oxygen and increased 

 carbon dioxide, flows from active than from passive muscle. 



4. If Q represent the numerical relation between the increase of 

 carbon dioxide and the decrease of oxygen as blood is converted 

 from the arterial into the venous state; that is to say, 



ifQ 



difference between C0 2 of arterial and venous blood 

 difference between O of arterial and venous blood 



then this quotient Q is found in most instances to be greater during 

 contraction of muscle than during repose. This might be due to the 

 fact that, in contraction, more carbon dioxide is generated for every 

 volume of oxygen absorbed, than in repose ; but since the precise seat 

 of the production of carbon dioxide is as yet but a matter of hypo- 

 thesis, we cannot at once draw this conclusion from the above experi- 

 ments. It may be merely that the forces which determine the 

 diffusion of carbon dioxide and oxygen respectively, are differently 

 affected by the condition of contraction; whence the change in the 

 relationship Q would be brought about, not by an increased gene- 

 ration of carbon dioxide, but by an increased elimination. 



The method of experiment which has just been de- 

 scribed is not free from objection. The uncontrollable 

 changes of the blood current in the course of an experi- 

 ment introduce a variable element which deprives the 

 results of all exact quantitative value. To meet this objection, and 

 to obtain results which should be strictly comparable, Ludwig and 

 Alex. Schmidt 1 devised 'a method of investigating the changes which 



Ludwig and A. Schmidt, loc. cit. 



