192 



PULSE. 



difference of 10 beats ; in a boy from four to 

 five years old, 16 beats ; and in a female, in 

 her 27th year, 10 beats. In two pregnant 

 women Hohl observed a difference of 10 and 

 1 1 beats respectively ; and the same author 

 reports a difference of from 20 to 40 beats in 

 new-born infants. He also attributes a re- 

 markable decrease of frequency sometimes 

 observed in the foetal pulse to the sleep of the 

 embryo. Other authors have been cognisant 

 of the effect of sleep, but have not made it 

 the subject of experiment. 



Food. The general effect of food is to 

 excite the pulse; this takes place to a very 

 slight extent with vegetable food, but more 

 with animal food. Some articles of diet, as 

 warm drinks, alcoholic liquors, and tobacco 

 have a very marked influence on the pulse. 

 The effect of food is much more considerable 

 in infancy than in after life. * 



Mental Emotions. The effect of these on 

 the pulse is too well known to require any 

 comment. 



Temperature of the Body. Cold lowers the 

 pulse, heat quickens it. Exposure to a very 

 high temperature causes a marked accelera- 

 tion. Thus Sir C. Blagden, on exposing 

 himself for 8 minutes to a temperature of 

 about 260, found his pulse rise to 144, or 

 double its ordinary frequency, f 



Density of the Air. In the observations 

 hitherto made, it is very difficult to separate 

 the influence of this agent from that of the 

 exertion which accompanied the change from 

 one medium to another. There was a very 

 considerable increase of frequency in the case 

 of the men who accompanied Saussure in the 

 ascent of Mont Blanc. The pulses that beat at 

 Chamounix 49, 66, and 72, became, on the 

 summit of the mountain, 98, 1 1^, and 100 re- 

 spectively. Dr. Clark also found the pulses 

 of his companions, in a state of rest on the 

 summit of the mountain, 84, 84, 88, 92, 102, 

 and 108 respectively, being a considerable 

 increase above the probable frequency of the 

 pulses of the same persons under ordinary 

 circumstances.;]: Miiller , on the authority 

 of Parrot, gives a table of the frequencies of 

 the pulse corresponding to different elevations. 

 They are as follows : Level of the sea, 70 ; 

 1000 metres, 75; 1500 metres, 82 ; 2000 me- 

 tres, 90 ; 2500 metres, 95 ; 3000 metres, 100 ; 

 4000 metres, 1 10. These numbers are pro- 

 bably unauthorised by experiments. 



The foregoing are some of the leading causes 

 which affect the frequency of the pulse in 

 health. They may be thrown into two 

 classes ; those which increase, and those 

 which diminish its frequency. 



1. The more common causes of increased 

 frequency of pulse are : Exercise, active and 

 passive ; continued muscular effort ; a change 

 from a posture requiring little, to one re- 

 quiring more exertion ; food, especially warm 



* Experiments of M. Valleix, Op. cit. p. 336. 

 t See Sir David Brewster's Natural Magic, p. 

 311. 



J See Auldjo's Ascent of Mont Blanc, p. 68. 

 Physiology, vol. i. p. 163. 



drinks ; spirituous liquors and tobacco ; a 

 high temperature ; diminished pressure of the 

 air; extreme debility ; sleeplessness ; the first 

 degree of plethora; and exciting passions and 

 emotions. 



2. The common causes of diminished fre- 

 quency of the pulse are, continued rest; 

 sleep ; fatigue, when not carried to excess ; 

 debility, when not extreme, and unaccompa- 

 nied by disease ; cold ; increased atmospheric 

 pressure ; a change from the erect to the 

 sitting, and from the sitting to the recumbent 

 posture, and the inverted position of the 

 body ; and depressing passions of the mind. 



Hitherto we have been speaking solely of 

 that character of the pulse which is most 

 easily examined, its frequency. To render 

 the subject complete, it will be necessary to 

 speak briefly of certain other characteristics 

 of the healthy pulse. 



The pulse of the healthy adult male may 

 be described as regular, equal, moderately full, 

 compressible, and swelling slowly under the 

 finger ; that of the female, and of the child of 

 both sexes, is smaller, and quicker in the 

 beat. The pulse of persons of the sanguine 

 temperament is full, hard, and quick ; that of 

 persons of the lymphatic temperament is 

 softer, and slower in the beat. In old age 

 the pulse, in consequence of the increased 

 firmness of the arteries, assumes a hardness 

 which would not otherwise belong to it. 



Exceptions to the general rule are not of 

 very rare occurrence in persons who enjoy 

 good health. There are some persons, for 

 instance, in whom every slight attack of 

 indigestion, especially when attended with 

 flatulence, leads to a well marked intermission. 

 Instances are also on record in which the 

 pulse is uniformly irregular or even distinctly 

 intermittent in health, becoming regular in 

 disease, and resuming its irregularity on re- 

 covery. 



One other subject connected with the phy- 

 siology of the pulse still remains to be exa- 

 mined, viz. 



THE RELATION OF THE PULSE TO THE 



RESPIRATION. The proportion which the 

 pulse bears to the respiration has been va- 

 riously stated by authors. Quetelet*, Parry-)-, 

 Burdach, and the greater number of physio- 

 logists estimate it as 4 to 1 ; Joy J as 4i to I ; 

 and Floyer as 5 to L M. Valleix states it 

 at 4 to 1 in infants. Little dependence, 

 however, is to be placed upon any of these 

 estimates, as they were made in ignorance of 

 the very remarkable effect of posture on the 

 respiration ; and as the respiration itself was 

 probably counted for very short intervals of 

 time, and under the disturbing influence of a 

 consciousness of the observation which was 

 being made. Though the posture of the body, 

 in which the pulse and respiration were 

 counted, is not distinctly stated by the authors 

 who have put forward the foregoing estimates, 



* Op. cit. vol. ii. p. 86. 



f Pathology, vol. i. 890. 



t Library of Practical Medicine, vol. iii. p. 274. 



Pulse Watch, p. 331. 



