214 CIRCULATION. 



very interesting character have been made by Dr. Guy and 

 others, with a view to determine the difference in the pulse 

 in different postures. In the male, there is a difference of 

 about ten beats between standing and sitting, and fifteen 

 beats between standing and the recumbent posture. In the 

 female, the variations with position are not so great. The 

 average given by Dr. Guy is, for the male : standing, 81 ; 

 sitting, 71 ; lying, 66 ; for the female : standing, 91 ; sitting, 

 84 ; lying, 80. This is given as the average of a large num- 

 ber of observations. There were a few instances, however, 

 in which there was scarcely any variation with posture, and 

 some in which the variation was much greater than the 

 average. In the inverted posture, the pulse was found to be 

 reduced about fifteen beats. 



The question at once suggests itself whether the accelera- 

 tion of the pulse in sitting and standing may not be due, in 

 some measure, to the muscular effort required in making the 

 change of posture. This is answered by the further experi- 

 ments of Dr. Guy, in which the subjects were placed on a 

 revolving board, and the posture changed without any mus- 

 cular effort. The same results as those cited above were 

 obtained in these experiments ; showing that the difference 

 is due to the position of the body alone. In a single obser- 

 vation, Dr. Guy found the pulse, standing, to be 89 ; lying, 

 77; difference, 12. With the posture changed without any 

 muscular effort, the results were: standing, 87; lying, 74; 

 difference, 13. 



Various theoretical explanations of these variations have 

 been offered by physiologists; but Dr. Guy seems to have 

 settled experimentally that the acceleration is due to the mus- 

 cular effort required to maintain the body in the sitting and 

 standing positions. The following are the results of experi- 

 ments which bear conclusively on this point, in which it is 

 shown that when the body is carefully supported in the erect 

 or sitting posture, so as to be maintained without muscular 

 effort, the pulse is less frequent than when the subject is 



