FREQUENCY OF THE RESPIRATORY MOVEMENTS 



lO/ 



with the inferior costal type is predominant, and this continues through 

 life. In the female the inferior costal type is insignificant and the 

 superior costal type predominates. The cause of the pronounced move- 

 ments of the upper part of the chest in the female has been the subject 

 of much discussion. It is probably due, in a great measure, to the 

 mode of dress now so common in civilized countries, which confines the 

 lower part of the chest and renders movements of expansion somewhat 

 difficult. In a series of observations by Dr. Thomas J. Mays (1887), 

 on eighty-two Indian girls at the Lincoln Institution in Philadelphia, 

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

 ing, 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 Hutchin- 

 son 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 themselves more readily than the male to the superior 

 costal type ; and this probably is a provision for the physiological en- 

 largement of the uterus in pregnancy, which nearly arrests respiratory 

 movements except those of the upper part of the chest. 



Frequency of the Respiratory Movements. In counting the respira- 

 tory acts, it is desirable that the subject be unconscious of the observa- 

 tion, otherwise their normal rhythm is likely to be disturbed. Of all 

 who have written on this subject, Hutchinson has presented the largest 

 and most reliable collection of facts. This observer ascertained the 

 number of respiratory acts per minute, in the sitting posture, in 1897 

 males. The results of his observations as to frequency are given in the 

 following table : 



RESPIRATIONS PER 

 MINUTE 



NUMBER OF 

 CASES 



9 to 16 79 



16 . . 239 



'7 



18 



19 



20 



74 



RESPIRATIONS PER 

 MINUTE 



NUMBER OF 

 CASES 



21 

 22 



23 

 24 



129 



143 



42 



243 



24 to 40 87 



Although this table shows considerable variations in different indi- 

 viduals, the great majority (1731) breathed sixteen to twenty-four times 

 per minute. Nearly a third breathed twenty times per minute, a number 

 that 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 



