202 A MANUAL OF PHYSIOLOGY 



Types of Respiration. Differences exist also, not only 

 between different groups of animals, but even between 

 women and men, in the relative importance in inspiration 

 of the diaphragm on the one hand, and the muscles that 

 elevate the ribs on the other. When the movements of the 

 diaphragm predominate, the respiration is said to be of the 

 abdominal on diaphragmatic type; when the movements of 

 the ribs and sternum are most conspicuous, of the costal or 

 thoracic type. In abdominal respiration, the inspiratory 

 movement commences at the diaphragm, and then involves 

 the lower ribs and the tip of the sternum. In costal 

 respiration, the upper ribs initiate the movement, and are 

 followed by the abdomen. In the rabbit, during quiet 

 breathing, the respiration is purely diaphragmatic, the ribs 

 remain motionless ; and herbivorous animals in general 

 conform more or less closely to this type. In the carnivora, 

 on the contrary, the costal type prevails. Man allies him- 

 self as regards his respiration with the rabbit and the sheep ; 

 he uses his diaphragm more than his ribs. Civilized woman 

 falls into the class of the wolf and the tiger ; she uses her 

 ribs more than her diaphragm. The cause of the difference 

 between men and women has been much discussed. It is 

 not a primitive sexual difference, for it is far from being 

 universal ; in the uncivilized and semi-civilized races that 

 have been investigated, the women breathe like the men. 

 It is therefore probable that the predominance of the costal 

 type among women of European race is a peculiarity 

 developed by a mode of dressing which hampers the move- 

 ments of the diaphragm while permitting the elevation of 

 the ribs. This conclusion is strengthened by the fact that 

 in children no difference exists ; both boys and girls show 

 the abdominal type of respiration. 



All this refers to ordinary breathing. In forced respira- 

 tion, when the need for air becomes urgent, costal breathing 

 always becomes prominent alike in men, in women, and in 

 animals, for by elevation of the ribs the capacity of the 

 chest can be increased to a greater degree than by any 

 contraction of the diaphragm. 



In forced inspiration, indeed, all the muscles that can 



