896 THE LUNGS. 



twecty-two ounces to twenty, taking the combined weight of the two at 

 forty-two ounces. The lungs are not only absolutely heavier in the male 

 than in the female, but appear to be heavier in proportion to the weight of 

 the body. The general ratio between the weight of the lungs and body, in 

 the adult, fluctuates according to the estimate of Krause, between one to 

 thirty-five and one to fifty. 



The following tables, deduced from Reid's and Hutchinson's observations, show the 

 average weight of the right and left lungs, and of both lungs together, and also the 

 relative weight of the lungs to the body in a certain number of adults of both sexes. 



AVERAGE WEIGHT IN TWENTY-NINE MALES AND TWENTY-ONE FEMALES. (REID.) 



MALE. FEMALE. 



Eight lung 24 oz 17 oz. 



Left lung 21 oz 15 oz. 



45 oz. 32 oz. 



AVERAGE IN TWENTY-FIVE MALES AND THIRTEEN FEMALES. (REID AND HUTCHINSON.) 



MALE. FEMALE. 



Proportionate weight of the lungs to the body ... 1 to 37 1 to 43 



The size and cubical dimensions of the lungs are influenced so much by their state 

 of inflation, and are therefore so variable, that no useful application can be made of 

 many of the statements given as to these measurements. It is important, however, 

 to ascertain the quantity of air which they contain under different conditions. This 

 subject has been investigated by many inquirers, whose statements on this point, 

 however, are exceedingly various. The volume of air contained in the lungs after 

 a forced expiration, has been estimated by Goodwyn at 109 cubic inches. After 

 an ordinary expiration it would seem that at least 60 cubic inches more are retained 

 in the chest, giving a total of 170 cubic inches in that condition of the lungs. The 

 amount of air inhaled and expelled in ordinary breathing has been very differently 

 estimated by different observers; it is most probably from 16 to 20 cubic inches. 

 According to the extensive researches of Hutchinson, men of mean height, between 

 five and six feet, after a complete inspiration, expel from the chest, by a forced expira- 

 tion, on an average, 225 cubic inches of air, at a temperature of 60. This quantity 

 is called by Hutchinson the vital capacity of the lungs. If to it be added the average 

 quantity found by Goodwyn to be retained in the lungs after complete expiration, viz. 

 109 cubic inches,' the result will yield 334 cubic inches of air at 60, as the average 

 total capacity of the respiratory organs for air in an adult male of ordinary height. 



The vital capacity (or difference between extreme expiration and extreme inspira- 

 tion) is found by Hutchinson to bear a very uniform relation to the height of the 

 individual, increasing at the rate of eight cubic inches for every additional inch of 

 stature above five feet. Its relations with the weight of the body are not thus regu- 

 larly progressive, for it appears to increase about one cubic inch for each additional 

 pound between the weights of 105 Ib. and 155 lb., or 7^ stones and 11 stones, and to 

 decrease at a similar rate between the weights of 11 and 14 stones, or 155 and 200 Ibs. 

 From the age of 15 to 35 years the vital capacity continues to advance with the growth 

 and activity of the frame, but between the ages of 35 and 65 it diminishes at the rate 

 of upwards of 1 cubic inch per annum. This differential or vital capacity is by no 

 means in proportion to the size of the thorax, whether that be estimated by the cir- 

 cumference of the chest, or by the sectional area of its base, or by its absolute capacity, 

 as ascertained by measuring its cubical contents after death. It is found rather, that 

 the vital capacity is strictly commensurate with the extent of the thoracic movements, 

 and with the integrity of the lungs themselves ; so that in phthisis, for example, it 

 becomes reduced by a quantity vary ing from 10 to 70 per cent., according to the stage 

 of the disease. A change from the erect to the sitting posture is accompanied by a 

 diminution of the vital capacity, which in one case fell from 260 to 255 cubic inches, 

 and on lying down, it was farther diminished to 230 cubic inches in the supine, and 

 220 cubic inches in the prone position of the body. Lastly, it is lowered by from 12 



