CHAPTER VII 



THE CALL FOR OXYGEN CONSIDERED AS A PHYSIOLOGICAL TEST 



AN advantage of the assurance that every increase in the activity 

 of the cell means an instant call for oxygen lies in the fact that it 

 furnishes a method of deciding whether in certain cases there is or is 

 not increased activity on the part of the cell. 



The most obvious instance in point is furnished by the kidney. 

 When Ringer's solution is injected into the blood of a cat or a rabbit, 

 there is an immediate increase in the amount of urine secreted. Yet 

 so far as may be judged from the nature of the secretion there is no 

 adequate reason to suppose either that there is or that there is not 

 increased activity on the part of the cells of the kidney. It might 

 be very plausibly supposed on the one hand that the mere fact of 

 increased flow of urine was an index of increased cellular activity 

 a view which I myself held till a few years ago. On the other hand 

 in this particular case the urine secreted is, so far as its crystalline 

 constituents are concerned, of the same composition as the plasma. 

 Therefore it is possible theoretically for the urine to be excreted as 

 the result of some change in the vascular conditions, the energy 

 necessary for the filtration being supplied by the heart. 



We* at once asked ourselves, Is there a call for oxygen? The 

 answer is sufficiently shown by the following experiment, a chart 

 of which is given in Fig. 60. 



The result is clear, there is no call for oxygen, no evidence of 

 work done by the cells as would have been the case if for instance 

 a solution of sodium sulphate had been injected, or some drug which 

 essentially altered the composition of the urine. This fact is sufficiently 

 shown by the following chart in which the oxygen used by the gland 

 and the volume of urine secreted are shown both during a diuresis 

 caused by sodium sulphate and one caused by Ringer's solution. 



* Dr Hermann Straub and myself. 



