THE LUNGS. 



1847 



FIG. 1568. 



External surface of lung, showing polygonal areas 

 corresponding to lobules mapped out by deposits of 

 pigniented particles within connective tissue. 



The weight of the lung is difficult to determine, owing to the impossibility of 

 quite excluding fluids. Sappey puts it at 60 or 65 gm. for the fcetus at term, and at 

 94 gm. on the average for the new-born infant that has breathed (thus show- 

 ing convincingly the worthlessness of the 

 method). Krause gives the adult weight 

 as 1300 gm. in the male and 1023 gm. in 

 the female. According to Braune and 

 Stahel, the weight of the right lung is to 

 that of the left as 100 : 85. 



The specific gravity of the lung be- 

 fore breathing is greater than that of water, 

 so that the lung sinks in it. Wilmart l has 

 recently stated it as 1068, which is the 

 same as Sappey 's statement and greater 

 than that of Krause (1045-1056). After 

 breathing it may be as little as 342, but 

 may go as high as 746. Probably figures 

 like the latter represent either diseased or 

 congested lungs. 



The dimensions are necessarily of lit- 

 tle value. According to Krause, the length 

 in man is 27.1 cm. on the right and 29.8 

 cm. on the left. In woman these dimen- 

 sions are 21.6 cm. and 23 cm. respectively. 

 There is little difference in length between 

 the lungs, but such as there may be is in favor of the left. The other dimensions 

 are probably more variable. According to Sappey, the antero-posterior diameter, 

 which increases from above downward, finally reaches 16 or 17 cm. Krause gives 

 the transverse diameter at the base in man as 13.5 cm. on the right and 12.9 cm. on 

 the left, and in woman as 12.2 cm. 

 and 10. 8 cm. respectively. 



The average capacity of the 

 lungs of a powerful man, after an 

 ordinary inspiration, is stated at from 

 34003700 cc. The vital capacity, 

 which is the greatest amount of air 

 that can be expelled in life after a 

 forced inspiration, is from 3200-3700 

 cc. for men and 2500 cc. for women. 

 The Bronchial Tree. The 

 plan of the bronchi of the human lung 

 (Fig. 1558) is as follows. The two 

 primary bronchi, resulting from the 

 bifurcation of the trachea, run down- 

 ward and outward into the lowest 

 lateral part of the lungs, the right 

 one descending more steeply. Their 

 course has been variously described. 

 That of the right one has been said 

 to resemble a C with the concavity 

 inward, and that of the left an S ; 

 but both comparisons are very forced. 

 On their way they give off secondary 

 bronchi, which are divided into ven- 

 tral and dorsal branches. The ven- 

 tral might more properly be called lateral, since they spring from the outer aspect of 

 the primary bronchus. They are much the larger, and supply all the lung, except the 

 apex and the posterior portion lying along the spine ; the latter is supplied by the 



1 La Clinique, 1897. 



FIG. 1569. 



Relations of bronchial tree to anterior thoracic wall, as shown 

 by X-rays. (After Blake.) 



