FREQUENCY OF THE RESPIRATORY MOVEMENTS. 127 



Philadelphia, between ten and twenty years of age, who had never worn tight 

 clothing, the abdominal type of respiration was found to predominate, the 

 respiratory tracings hardly differing from the tracings in the male. These 

 observations seem to show, in opposition to the views of Hutchinson and 

 others, that the predominance of the superior costal type in the female is 

 confined to civilized races ; but it is certain that females accommodate them- 

 selves more readily than the male to the superior costal type ; and this is 

 probably a provision against the physiological enlargement of the uterus in 

 pregnancy, which nearly arrests all respiratory movements except those of the 

 upper part of the chest. In pathology it is observed that females are able to 

 carry, without great inconvenience, a large quantity of water in the abdominal 

 cavity ; while a much smaller quantity, in the male, produces great distress 

 from difficulty of breathing. 



Frequency of the Respiratory Movements. In counting the respiratory 

 acts, it is desirable that the subject be unconscious of the observation, other- 

 wise their normal rhythm is likely to be disturbed. Of all who have written 

 on this subject, Hutchinson has presented the largest and most reliable col- 

 lection of facts. This observer ascertained the number of respiratory acts 

 per minute, in the sitting posture, in 1,897 males. The results of his ob- 

 servations, with reference to frequency, are given in the following table : 



RESPIRATIONS PER MINUTE. NUMBER OP CASES. 



9 to 16 79 



16 239 



17 105 



18 195 



19 74 



20 561 



21 129 



22 143 



23 42 



24 243 



24 to 40 87 



Although this table shows considerable variation in different individuals, 

 the great majority (1,731) breathed sixteen to twenty-four times per minute. 

 Nearly a third breathed twenty times per minute, a number which may be 

 taken as the average. 



The relations of the respiratory acts to the pulse are quite constant in 

 health. It has been shown by Hutchinson that the proportion in the great 

 majority of instances is one respiratory act to four pulsations of the heart. 

 The same proportion generally obtains when the pulse is accelerated in dis- 

 ease, except when the pulmonary organs are involved. 



Age has an 'influence on the frequency of the respiratory acts, correspond- 

 ing with what has already been noted with regard to the pulsations of the 

 heart. 



The following are the results of observations on 300 males (Quetelet) : 



44 respirations per minute, soon after birth ; 



