THORAX. 



1059 



circumference over the nipples, alive, 38 in. ; 

 dead, 36 in. died with an expiration, we, 

 by means of the hamiadynamometer, contain- 

 ing water, attached to the trachea, found, 

 with different volumes of air in the lungs, 

 the following elastic collapsing power (tem- 

 perature of body 98'5 Fahr. of atmo- 

 sphere 59'5, barometer 29-753). 



TABLE O. Elasticity of the Lungs (male, 

 set. 29.). 



Elastic col- 

 lapsing power, 



* Volumes of air. in. of water. 

 Residual vol. - 2'5 

 Reserve vol. (+90 cubic inches) 7-2 

 Breathing vol. ( + 20 ditto) - 8'2 

 Vital capacity (+25 ditto +150 



ditto) - - - - - 17'0 

 M. M., female ; sudden death ; temperature 

 of body 97-5 Fahr. ; set. 28 ; height 5 ft. 9 in.; 

 circumference of chest over nipples 37 in.; 

 below 32* ; lungs healthy, 

 TABLE P. Elasticity of Lungs (fern., aet. 28.). 



Elastic col- 

 lapsing power, 

 VoHimes of air. in. of water. 



Residual vol. - - - - 0'7 

 Reserve vol. (+ 100 cubic inches) 5'5 

 Breathing vol. (+ 100 ditto) lO'O 

 Vital capacity (+ 90 ditto) 20'0 



At the commencement of "ordinary breath- 

 ing" the collapsing power of the lungs in 

 our experiment was 7*2 in., or nearly of 

 a Ib. per superficial square inch. This is a 

 very notable power, not less in the gross, 

 oftentimes, than 100 Ibs. of dead uncounter- 

 balanced resistance to the respiratory mus- 

 cles. In the female, with nearly an arith- 

 metical increase of 100 cubic inches per vo- 

 lume, the collapsing power increases 5 to 10 

 and 20. The insufflated volume in the male 

 being less regular, the collapsing power ma- 

 nifested is also less regular. But, taking the 

 mean resistance of the reserve and breathing 

 volumes in the male combined (160 cub. in.), 

 the power of collapse was 7'7 inches. In the 

 female, the mean of nearly the same quantity 

 of air in the lungs (within 10 cubic inches) 

 allowing for little or no residual volume at the 

 starting point when we inflated, is likewise 

 7'7 inches. We believe that the elastic power 

 of the lungs in the two sexes is the same; 

 indeed why should it not be so? because 

 the office of the elastic tissue is to drive 

 out of the lungs volumes of air no longer 

 required ; and it is probable that the resistance 

 given by the air, against the sides of the air 

 tubes, in both sexes, is the same; and unless 

 the number and calibre of the air tubes are 

 different, the resistance, by friction, to the 

 elastic collapse of the lungs, from the trans- 

 mission of similar volumes of air in the two 

 sexes, must be the same. 



In three experiments we found the elastic 

 collapse of the lungs cease at different degrees ; 

 i. e. different volumes of residual air were 

 displaced when the elastic force had come to 

 its minimum. 



* For definition of these terms see p. 1065. 



TABLE Q, Volume of Residual Air displaced by 



the Elastic Collapse of the Lungs when the 

 Thorax was opened, in three Males. 



There is no order in the numbers 30, 60, and 

 45, relative to the other measurements. We 

 do not know what quantity of air remained after 

 these volumes were displaced. When we ex- 

 hausted the remainder of the residual volume, 

 which is not affected by the elastic collapse of 

 the lungs, the sides of the air tubes themselves 

 collapsed by the atmospheric pressure. They 

 likewise are elastic, but in a contrary direc- 

 tion; an expanding elasticity keeping them 

 open. We found that the expanding elasticity 

 acted so as to draw or suck inwards the air 

 with the different powers represented by 7, 1*5 

 and 12'5 inches of water in the haemadynamo- 

 meter, when we attempted to withdraw out of 

 the lungs more air than the lungs themselves 

 naturally displace by their collapsing elasticity. 

 Therefore these figures may represent the ex- 

 panding elasticity of the air tubes. In these 

 cases there is no apparent order ; but we learn 

 the fact that such elasticity exists. In the 

 case C there was a tubercular condition of 

 lung, in the milliary form, in one apex j in H 

 there was extensive pleuritic adhesions ; but 

 in the case of M the lungs were remarkably 

 healthy. It is interesting to notice that there 

 are here two elasticities in contrary direc- 

 tions, an elastic collapse which has its limit 

 at a certain point, and an elastic expansion 

 of the air tubes, which likewise have their 

 limit of expansion at the same point, protecting 

 the calibre of the air tubes from any further 

 collapse. 



In the case of M the expansion of the air 

 tubes was equal to 12'5 inches of water; by 

 calculation it appears that the col/apse of the 

 elastic tissue upon the vital capacity volume 

 would be about 14 inches. These antago- 

 nistic forces are quite independent of the will, 

 or any nervous stimuli : one is for maintain- 

 ing an expiratory current of air, and the other 

 for preserving an open channel in the lungs for 

 inspiration. 



The lungs are very delicate organs, and can 

 resist but little artificial force ; for, if once 

 inflated to the ordinary state of either the 

 breathing volume or vital capacity volume, 

 they do not appear able to collapse again to 



their original size ; probably intra-lobular 



emphysema is produced. 



In our experiments we forced air into the 



lungs; they were expanded because we inflated 



them. We now think it would be better to 



3v 2 



