RESPIRATION IN MAN 195 



dissecting-room subjects varying in age from fifty to seventy- 

 two years, in whom the compressibility of the thorax is expected 

 to be greatly diminished. 



Results of Compression of the Thorax* Living. Dead. 



1. The front-to-back diameter of the thorax was 



diminished in turning from the supine to 



the prone position 17'4 mm. 21*4 mm. 



2. The side-to-side diameter in the same experi- 



ment increased 22'1 mm. 13-5 mm. 



3. The front-to-back diameter decreased on 



placing 10 kilos, on the thorax (subject 



supine) 23'7 mm. 29'6 mm. 



4. The transverse diameter increased in the same 



experiment 5'6 mm. 13*5 mm. 



5. The front-to-back diameter of the thorax de- 



creased on placing 10 kilos, on the thorax 



(subject prone) ...... 12'8 mm. 4-6 mm. 



6. The transverse diameter increased in the same 



experiment 3'0 mm. 8'6 mm. 



These experiments show that the compressibility of the thorax is 

 largely modified by the action of muscles during life, and that in 

 the prone position a very great degree of the natural elasticity 

 of the thorax is lost. 



Freund, whose observations are receiving active attention in 

 Germany, after many years of neglect, is of opinion that the 

 elastic torsion which occurs in the cartilage of the first rib during 

 inspiration is one of the chief active forces in producing an 

 expiratory recoil of the thorax ; he also regards emphysema as a 

 result of loss of elasticity of the costal cartilages. His opinion 

 concerning the expiratory recoil of the cartilage of the first rib 

 will be .referred to in dealing with the sterno-manubrial joint ; as 

 regards the loss of elasticity of the cartilages causing emphysema, 

 it may be said that surgeons have put Freund's belief into practice 

 by section of the costal cartilages in such cases, but the results 

 of such experiments have not yet been determined. Certainly 

 calcification of the costal cartilages frequently occurs without 

 emphysema. 



