132 Mr. Le Gros Clark on the Mechanism of Respiration. 



24. In ordinary expiration no muscular action is exerted ; but in extra- 

 ordinary expiration the ribs are drawn down by the abdominal muscles, at 

 the same time that the abdominal viscera are pressed upwards. The in- 

 tercostals assist in this act when the lower ribs are thus fixed. The levator 

 ani is an essential auxiliary in forced expiration. I do not attach much value 

 to the agency of the triangularis sterni and serratus posticus inferior as 

 muscles of expiration. I am disposed rather to regard them as agents in 

 steadying the ribs for the diaphragm, and as antagonists, severally, to the 

 pectoral and latissimus dorsi muscles, thereby affording them a more fixed 

 attachment at their origin. 



25. The generally received assertion that there is a marked difference 

 in the respiration of the two sexes, i. e. man and woman, confirmed, 

 apparently, by the observations of Hutchinson on young girls, has always 

 struck me as very remarkable ; for, whatever hypothesis may be adduced 

 to favour the relative advantage of such peculiarity, as regards woman, 

 there certainly is no anatomical difference, either in the natural osseous 

 conformation of the chest or in the muscular apparatus of respiration, to 

 account for the predominance of the abdominal type of breathing in the 

 male, and of the thoracic type in the female. 



It naturally occurs to any one, in contemplating this circumstance, to 

 attribute something to the peculiar dress of civilized women — the fashion of 

 compressing the lower part of the chest, which is universal. There can 

 be no doubt that this compression, commenced as it is at a very early 

 period amongst all classes, long before the development of the skeleton is 

 completed, must exercise a permanent influence in altering the form of the 

 chest, and must thus impart a factitious reality to that which is not 

 natural. I believe that the early age at which this compression is begun, 

 even amongst the lower orders, as I have ascertained by inquiry, has 

 possibly misled so careful an observer as Hutchinson. I have repeated 

 his experiments on young boys and girls, but with results at variance with 

 those which he obtained. These results may be thus stated. 



26. In ordinary respiration the upper costal respiratory movements 

 are equal in male and female ; they are increased in both by girding the 

 abdomen and lower ribs with a roller. The lower cosial movements are 

 also equal in the two sexes, and are not percep tibly affected by the action 

 of the roller. 



The difference in the thoracic girth between ordinary expiration and 

 inspiration is very slight, indeed scarcely perceptible. 



27. In extraordinary respiration the costal movements, both upper 

 and lower, are much greater in forced inspiration in the male than in the 

 female. The lower costal movements are much interfered with, in both, by 

 the compression of the abdomen and lower part of the chest, while the 

 upper costal movements are exaggerated. 



I may add that, in the adult female, there is, as might be expected, a 

 striking difference in the relative mobility of the chest and abdomen, when 



