36 David H. Dolley, 



was the first, had studied the physiologic action of the products of 

 cellular activity and had found them marked. It was thus most 

 natural that the idea should arise that these coincident phenomena 

 are in correlation. In the full development of this, idea, the fatigue 

 substances are supposed to stand in a causal relation to the anatom- 

 ical changes. 



It is true that it is not usually stated in so many words in the 

 literature. It is rather suggested or to be inferred from the emphasis 

 laid on the reaction of the waste products. That the idea is fre- 

 quently uppermost in the minds of physiologists, however, the writer 

 has become convinced as a result of conversations with several on his 

 extension of Hodge's work on functional activity. Invariably the first 

 point raised was the relation of toxic waste products or the first 

 question, „Have you tried the effect of lactic acid?" 



The purpose of this paper is the presentation of the results 

 obtained from administration of such substances, the conclusions based 

 thereon in regard to the distinction between ifunctional activity and 

 functional depression and, finally, the error which has resulted from 

 the neglect of this distinction. The experiments, here originally 

 presented, whose results eliminate the waste products as the cause of 

 the changes peculiar to normal function will first be described and 

 discussed. 



Experimental Data. 



Transfusions from fatigued animals. — The procedure here was 

 to work a dog in the treadmill to a point which previous experience 

 (1909 c) had shown was associated with profound and widespread 

 cellular exhaustion. With both this donor and the future recipient 

 dog under ether anesthesia, the blood was first withdrawn from the 

 recipient to accommodate the incoming blood from the fatigued donor. 

 Transfusion was then made. After a short wait for thorough diffu- 

 sion of the foreign blood within the recipient , the bleeding was 

 repeated in order to get out as much original blood as possible and 

 then a final transfusion was done. 



First in the series, a group experiment was performed, in which 

 six puppies of the same litter, barely six weeks old, were used. Two 



