216 CIRCULATION. 



states, as the result of observation, that a man in the recum- 

 bent position has 64 pulsations per minute ; after a slow walk, 

 78 ; after walking a league and a half in an hour, 100 ; and 

 140 to 150 after running with all his might. 1 This general 

 statement, which has been repeatedly verified, shows the 

 powerful influence of the muscular system on the heart. The 

 fact is so familiar that it need not be further dwelt upon. 



The influence of sleep upon the action of the heart reduces 

 itself almost entirely to the proposition, that during this con- 

 dition, we have an entire absence of muscular effort, and 

 consequently the number of beats is less than when the in- 

 dividual is aroused. It has been found that there is no differ- 

 ence in the pulse between sleep and perfect quiet in the 

 recumbent posture. This fact obtains in the adult male ; but 

 it is said by Quetelet that there is a marked difference in 

 females and young children, the pulse being always slower 

 during sleep. 2 



Influence of Temperature. The influence of extremes of 

 temperature upon the heart is very decided. The pulse may 

 be doubled by remaining a very few minutes exposed to ex- 

 treme heat. Bence Jones and Dickinson have ascertained 

 that the pulse may be very much reduced in frequency, for 

 a short time, by the cold douche. 3 It has also been remarked 

 that the pulse is habitually more rapid in warm than in cold 

 climates. 



Though many circumstances materially affect the rapidi- 

 ty of the heart's action, they do not complicate, to any great 

 extent, our examinations of the pulse in disease. In cases 

 which present considerable febrile movement, the patient is 

 generally in the recumbent posture. The variations induced 

 by violent exercise are easily recognized, while those depend- 

 ent upon temperature, the condition of the digestive system, 

 etc., are so slight that they may practically be disregarded. 



1 MILNE-EDWARDS, Lemons sur la Physiologic, tome iv., p. 68. 



2 Ibid. 



3 Journal de la Physiologic, 1858, tome i., p. 72. 



