46 THORAX 



are healthy and not hardened, the dissectors found when 

 they opened the pleurae that the lungs shrank to about 'one- 

 third of their original bulk (see p. 19). In such cases, with 

 the consent of the dissectors of the head and neck, the 

 dissectors have already distended the lungs and examined 

 their elasticity (see p. 23). 



The weight of an adult healthy right lung, containing an 

 average amount of blood, is about 620 grm. (22 oz.), and 



Trachea 



Subclavian sulcus 

 Groove caused 

 by the first rib 



Subclavian sulcus 



Lower lobe 



Cardiac notch 



Lower lobe 



FIG. 1 6. The Trachea, Bronchi, and Lungs of a Child, hardened 

 by formalin injection. 



that of the left is 570 grm. (20 oz.). The whole lung, or any 

 healthy portion of it, will float in water. 



A lung which will not float in water is either diseased or it has been 

 taken from the body of an infant which has not breathed. Before the first 

 respiration, which takes place after birth, the lungs are solid organs, and 

 their bulk is small in proportion to their weight ; therefore, when they 

 are removed from the body and placed in water they sink. 

 



The lungs, when healthy and sound, lie free within the 

 cavity of the chest, and are attached only by their roots and 

 by their pulmonary ligaments. It is rare, however, that a 



