PHYSIOLOGICAL CHANGES IN TRANSITION. 



301 



shown in curve D are practically constant, varying from 0.44 to 0.48 

 second throughout a record of three-quarters of a minute, thus indi- 

 cating a more uniform duration of the pulse-cycle than that shown 

 by curve C. The second record taken by this method (curve E) 

 was made after a total period of walking of 30 minutes. During the 

 144 cycles in this curve, the length of cycle varied only from 0.37 to 

 0.39 second. These two records show a remarkably constant cycle 

 duration after a sufficient period of time had elapsed for the body to 

 become adjusted to the needs of the exercise of walking. While they 



0.50 r 



.60 

 .70 

 .80 

 .90 



.30 

 .40 

 .50 



.60 

 .70 

 .80 

 .90 



4 



1.00 

 1.10 



Ul 



O 

 O 



UJ 



LL 



o 



Z" 

 O 



A 



AJ! 



en 



D 



a 



1.20 



30 



10 20 30*40 50 30 20 10 10 20 30 40 50 60 70 80 90 100 110 

 PULSE CYCLES 



FIG. 41. Duration of pulse-cycles of E. D. B. in grade-walking experiment of February 29, 1916, 

 as indicated by averages of two pulse-cycles measured individually. 



A, standing; B, transition standing to walking, beginning of walking at X. C, walking 26 min- 

 utes after X. D and E, standing 8 and 14 minutes, respectively, after end of walking. 

 All curves except B with lengthened record of time-interval. The time required for groups 

 of cycles, varying in number, is indicated for curve B by small figures and inclusion marks 

 at the bottom of the chart. 



also indicate that the irregularities in the duration of the pulse-cycle 

 in the few seconds preceding walking may in part be due to errors of 

 measurement, it is believed, for reasons given later, that these irregu- 

 larities are present, and that the relative behavior of the pulse for stand- 

 ing and walking as shown by the curves in figure 40 is correct. 



