TEXTURE AND COXSISTEXCE. 271 



AVERAGE IN TWENTY-FIVE MALES AND THIRTEEN FEMALES. — (KEID AND 



HUTCHINSON.) 



MALE. FEMALE. 



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



The .ii:c and cuhlcal dimensions of the kings are influenced so much by their 

 state of inflation, and are therefore so variable, that no useful aj^plication can be 

 made of many of the statements given as to these measurements. It is im- 

 portant, 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 ail" contained in the lungs after a forced expiration, was found by Grehant to be 

 about .57 cubic inches. After an ordinary expii-ation it would seem that about as 

 much more is retained in the chest. The amount of air inhaled and expelled in 

 ordinary breathing has been very differently estimated by different observers ; it 

 is most probably about ."() cubic inches. According to the extensive researches of 

 Hutchinson, men of mean height, between five and six feet, after an extreme 

 inspii-ation. exjiel from the chest, by a forced exi^iration, on an average. 225 cubic 

 inches of air, at a temperatm-e of (30^. This quantity is called by Hutchinson 

 the vital capacity of the lungs. It would be better tenned cdvemc (I'iffcvcntlal 

 capacltij. If to it be added the average quantity found by Grehant to l)e re- 

 tained in the hmgs after comjilete expu'ation, the result will yield 282 cubic inches 

 of air at 60^, as the average total capacity of the resi^katory organs for air in au 

 adult male of ordinary height. 



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

 spiration) was found by Hutchinson to bear a uniform relation to the height of 

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

 inch of statm-e above five feet ; but this relation is affected by the weight and 

 age of the individual, as well as by the postui-e of the body. It seems to depend 

 rather on the mobility than the size of the chest. (Hutchinson, in Journal of 

 Statistical Society, August, 1844 ; and in Medico-Chirui-g. Transactions, vol. xxix., 

 184G ; also in the article '• Thorax,"' in Cyclopasdia of Anatomy and Physiology, 

 and the article " Resjjiration," by Reid, in the same.) 



Texture and consistence. — The substance of the lung is of a light 

 porous spongy texture, and, when healthy, is buoyant in water : but in 

 the foetus, before respiration has taken place, and also in certain cases 

 of congestion, collapse, or consolidation from disease, the entire lungs, 

 or portions of them, sink in that fluid. The specitic gravity of a 

 healthy lung, as found after death, varies from 0*345 to 0746. When 

 the lung is fully distended its specific gravity is 0"126, whilst that of the 

 pulmonary substance, entirely deprived of air, is 1'056 (Krause). When 

 pressed between the fingers, the lungs impart a crepitant sensation, 

 which is accompanied by a peculiar noise, both effects being caused by 

 the air contained in the tissue. On cutting into the lung, the same 

 crepitation is heard, and there exudes from the cut surface a reddish 

 frothy fluid, which is partly mucus from the air-tubes and air-cells, and 

 partly a serous exudation, tinged with blood, and rendered frothy by 

 the admixed air. 



The .pulmonary tissue is endowed with great elasticity, in conse- 

 quence of Avhich the lungs collapse to about one-third of their bulk 

 when the thorax is opened. Owing to this elasticity also, the lungs, if 

 artificially inflated out of the body, contract to their j)revious volume 

 when the air is again allowed to escape. 



Colour. — In infancy the lungs are of a pale rose-pink colour, which 

 might be compared to blood-froth ; but as life advances they become 

 darker, and are mottled or variegated with spots, patches, and streaks 



