Pulse and Respiration. 



101 



from 55 to 66 beats per minute. The second cycle reaches 80, the 

 third 77; the rise is then more gradual, being 76, 73, 74, and 74, or a 

 pulse rate of 81 beats per minute. Immediately upon the relaxation 

 of the muscles the cycle lengthens, dropping to 86. From this point 

 during next 8 pulse cycles the duration gradually decreases (shortens) 



664321 1234667123466789 10 12 14 16 18 20 



Fig. 12. — Average duration of pulse cycles given in hundredths of a second for pre-tetanus, 

 tetanus, and post-tetanus periods on three normal and three alcohol days, after the 

 control or normal dose. 



until it reaches 75, very nearly the duration in the latter part of the 

 tetanus section (73). It remains at 75 (80 beats per minute) for 3 

 pulse cycles, then in 9 cycles it decreases to the level of 107 (56 beats 

 per minute) or very nearly the level immediately before tetanus. 



The curve under discussion is of course based upon the records taken 

 on one subject only, and in the absence of similar data on other sub- 

 jects no exact comparison can be drawn or proof given concerning the 

 accuracy of its representation of the changes in pulse rate occasioned 

 by the type and duration of exercise employed. However, that por- 

 tion of the curve which shows the transition from rest to exertion is 

 believed to be representative, since it is in perfect agreement with the 

 data of Bowen 1 , Buchanan, 2 and Krogh and Lindhard 3 in demonstra- 



1 Bowen, Contributions to Medical Research dedicated to Victor Clarence Vaughn, June 1903, 

 p. 462, Ann Arbor, Mich. 



2 Buchanan, Trans. Oxford Univ. Junior Scientific Club, n. s., No. 34, 1909, p. 351; reprinted in 

 the Smithsonian Report for 1910, pp. 487-505; Science Progress No. 17, July 1910, p. 60. 



3 Reported by Krogh and Lindhard, Journ. Physiol., 1913, 47, p. 117. 



