544 THE OUTGO OF ENERGY 



for example, before and after lifting the weight 

 of the body ten times by rising on the toes. 



Sex, eating, the time of day, the temperature, 

 and many other factors also influence the fre- 

 quency of the pulse. 



Hardness. When pressure is made upon an 

 artery in any part of its course, the pressure is 

 transmitted in all directions through the liquid 

 contained in the peri-arterial tissues, and the 

 artery becomes smaller. Part of the pressure is 

 used upon the peri-arterial tissues themselves. 

 When the remaining pressure equals the maxi- 

 mum blood-pressure in the artery at the point of 

 compression, the blood-pressure on the distal 

 side of this point will sink to the level of the 

 blood-pressure in the nearest anastomosis. If 

 the anastomosis is of capillary size, the pulse will 

 disappear. A pulse which is obliterated by slight 

 pressure is termed " soft ; " if the pressure re- 

 quired is relatively considerable, the pulse is 

 termed " hard." The hardness of the pulse is 

 therefore a measure of the maximum blood- 

 pressure at the point of compression, less the 

 variable and unknown quantity required for the 

 compression of the elastic tissues. 



Form. 1. The vibrations which follow the 

 primary pulse wave cannot ordinarily be recog- 

 nized by the palpating finger. When, however, 



