132 RESPIRATION. 



At a variable period after birth, a difference in the types of respiration in the sexes 

 begins to show itself. In the male, the abdominal conjoined 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. Observers differ in their state- 

 ments of the period of life when this distinction in the sexes becomes apparent. Without 

 discussing the nice question as to the exact age when this difference in the sexes first 

 makes its appearance, it may be stated, in general terms, that, shortly before the age of 

 puberty in the female, the superior costal type becomes more marked and soon predomi- 

 nates ; while, in the male, respiration continues to be carried on mainly by the diaphragm 

 and lower part of the chest. 



The cause of the excessive movements of the upper part of the chest in the female has 

 been the subject of considerable discussion. It is evident that it is not due to the mode 

 of dress now so general in civilized countries, which confines the lower part of the chest 

 and would render movements of expansion somewhat difficult, for the same phenomenon 

 is observed in young girls and others who have never made use of such appliances. But 

 there is evidently a physiological condition, the enlargement of the uterus in gestation, 

 which, at certain times, would nearly arrest all respiratory movements, except those 

 of the upper part of the chest. The peculiar mode of respiration in the female is a pro- 

 vision of Nature against the mechanical difficulties which would otherwise follow the 

 physiological enlargement of the uterus. In pathology it is observed that, in consequence 

 of this peculiarity, females are able to carry, without great inconvenience, immense quan- 

 tities of water in the abdominal cavity ; while a much smaller quantity, in the male, pro- 

 duces great distress from difficulty of breathing. 



Frequency of the Respiratory Movements. In counting the respiratory acts, it is de- 

 sirable that the subject be unconscious of the observation, otherwise their normal char- 

 acter is apt to be disturbed. Of all who have written on this subject, Hutchinson pre- 

 sents the most numerous and convincing collection of facts. This observer ascertained 

 the number of respiratory acts per minute, in the sitting posture, in 1,897 males. The 

 results of his observations, with reference to frequency, are given in the following table: 



Respirations per minute. Number of cases. 

 From 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 (1,781) breathed from 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 every four pulsations of the heart. The same proportion generally 

 obtains when the pulse is accelerated in disease, except when the pulmonary organs are 

 involved. 



Age has an influence on the frequency of the respiratory acts, corresponding with 

 what we have already noted with regard to the pulsations of the heart. 



