208 



RESPIRATION. 



ment appears less extensive in the lower, and more so in 

 the upper, part of the chest ; a mode of breathing to which 

 a greater mobility of the first rib is adapted, and which 

 Tig. 63.* fig. 64.f 



S f 



may have for its object the provision of sufficient space for 



* Fig. 63 . (after Hutchinson). The changes of the thoracic and 

 abdominal walls of the male during respiration. The back is supposed 

 to be fixed in order to throw forward the respiratory movement as much 

 as possible. The outer black continuous line in front represents the 

 ordinary breathing movement: the anterior margin of it being the 

 boundary of inspiration, the posterior margin the limit of expiration. 

 The line is thicker over the abdomen, since the ordinary respiratory 

 movement is chiefly abdominal : thin over the chest, for there is less 

 movement over that region. The dotted line indicates the movement 

 on deep inspiration, during which the sternum advances while the 

 abdomen recedes, 



f Fig. 64 (after Hutchinson). The respiratory movement in the female. 

 The lines indicate the same changes as in the last figure. The thickness 

 of the continuous line over the sternum shows the larger extent of the 

 ordinary breathing movement over that region in the female than in 

 the male. 



