390 RESPIRATION. 



The abdominal type is most marked in children under 

 the age of three years, irrespective of sex. In them, respira- 

 tion is carried on almost exclusively by the diaphragm. 



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 pre- 

 dominant, and continues thus through life. In the female the 

 inferior costal type is insignificant, and the superior costal 

 type predominates. Observers differ in their statements of 

 the period when this distinction in the sexes becomes appa- 

 rent. Haller states that he observed a difference in children 

 less than a year old. Beau and Maissiat state that after the 

 age of three years the superior costal type begins to be marked 

 in the female. Sibson states that no great difference is ob- 

 servable before the age of ten or twelve years. 1 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 pu- 

 berty, in the female, the superior costal type becomes more 

 marked, and soon predominates ; while in the male, respira- 

 tion 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 ex- 

 pansion somewhat difficult, for the same phenomenon is ob- 

 served 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 move- 

 ments, excepting those of the upper part of the chest. The 

 peculiar mode of respiration in the female is a provision of 

 Nature against the mechanical difficulties which would other- 



1 LONGET, Traite de Physiologic, Paris, 1861, tome i., p. 617. 



