PULSE DURING MENTAL AND PHYSICAL WORK. 233 



experiments this was shown in a flattening out of the experimental 

 change after alcohol. In the pulse-acceleration of physical work the 

 effect of alcohol is greater immediately after the exercise; 60" later it 

 is conspicuously less. 



CAUSE OF THE RELATIVE ACCELERATION OF THE PULSE AFTER ALCOHOL. 



While a positive acceleration of the pulse after the ingestion of alcohol 

 is found only occasionally in the succeeding periods of our experimental 

 sessions, relative acceleration is, as we have seen, almost universal. By 

 relative acceleration we mean a more rapid pulse than occurs at homolo- 

 gous periods of normal days. 



It seems possible that some part of the discrepancies in the literature 

 which we cited in the first section of this chapter, with respect to the 

 effect of alcohol on the pulse-rate of both man and animals, results 

 from a confusion between positive and relative acceleration. In the 

 ordinary course of investigation it requires especial and insistent 

 emphasis on normal experiments to detect relative acceleration. In 

 operative techniques it is often difficult if not impracticable to secure 

 homologous normal experiments in sufficient number for the detection 

 of relative changes. Even when practicable it often seems like a 

 waste of material. But where the alcohol effects are small and 

 necessarily superposed on normal or other experimental rhythms, we 

 believe that our data show the value of careful comparative treatment. 

 To indicate a probable partial cause in the discrepancies of traditional 

 data we believe to be almost as useful as direct data in our attempt 

 to solve the alcohol problem. Other and more significant causes of dis- 

 crepancy will appear in the following discussion. 



In our experiments at least, relative acceleration of the pulse occurs 

 in greater or less degree in all subjects as a part of the effect of alcohol 

 on the pulse during a considerable variety of mental and physical 

 activities. The large number of our records and the variety of the 

 processes permit us to make the following generalization: A regular 

 effect of moderate doses of alcohol on temperate non-abstainers during 

 intermittent mental and physical activity is a relative acceleration of 

 the pulse. The fact is quite unequivocal in our records, but it consti- 

 tutes a clear exception to our other experimental results. In no other 

 case have we found consistent increase of a function as a result of the 

 ingestion of alcohol. 



The cause of the relative acceleration of the pulse after alcohol thus 

 becomes a question of considerable theoretical importance. As is well 

 known there are two reciprocating mechanisms that determine the rate 

 of heart-contraction. The classical paper of Reid Hunt 1 is generally 

 credited with the demonstration that increased pulse-rate after the 

 beginning of muscular activity is commonly produced by a depression 

 of the heart inhibitor as well as by a stimulation of the accelerator. 



, Am. Journ. Physiol.. 1899, 2, p. 395. 



