1823.] an Operation for Phthisis Pubnonalis. 435 



that of pulsation, neither was it synchronous with the action of 

 the heart, but it was a slow undulating movement. On closino- 

 the gash, and keeping it so for four or five inspirations, then 

 opening it quickly, the lung was found to have increased in 

 volume ; on exposure, it again diminished. To close the scene, 

 the knife was plunged into the heart with a determination never 

 to perform another experiment on a living animal, which I 

 had been induced in the present case to do, by my anxiety to 

 solve an important practical problem. 



I believe no one has ever appreciated the power of the luno\s 

 and their auxiliaries in respiration during life in resisting and 

 diminishing the pressure of the atmosphere, when admitted into 

 the cavities of the thorax through apertures in its parietes. 

 That they do possess a considerable power is beyond a doubt. 

 The oppression of the breathing and the expansion of the lungs 

 are in an inverse ratio to one another, and can be regulated by 

 adjusting the dimensions of the openings into the cavities of the 

 chest. As the apertures increase in their size, the power of 

 expansion of the lungs is diminished, while the oppression of 

 the breathing is augmented, until at last life is extinguished. 

 What quantity of air is sufficient to produce death as long as all 

 the respiratory organs are not restrained, I have not ascer- 

 tained. The doctrine of the lung collapsing, while the function 

 of the opposite one is unimpaired, on exposure of its external 

 surface to the atmosphere, taught from time immemorial in the 

 schools, I must now consider as erroneous, and feel somewhat 

 surprised that a notion so groundless should have existed for so 

 many ages. 



From the foregoing experiments, it appears, 



1. That a lung will not collapse from exposure to the atmo- 

 sphere as long as respiration is carried on by the opposite one, 

 and the auxiliary respiratory powers are not restrained. 



2. That a lung possesses for a time, independently of the 

 influence of the diaphragm and intercostal muscles, if respiration 

 is carried on by the opposite lung, a peculiar motive power, the 

 source of which I do not pretend to explain. 



3. That a sound lung soon regains its full power of expansion, 

 when the pressure of the exterior air is removed. 



4. That air freely and uninterruptedly admitted into both 

 cavities of the chest simultaneously, through tubes of a certain 

 calibre, will not collapse the lungs, if the auxiliary respiratory 

 organs arc unrestrained. 



5. That air admitted into both the cavities of the chest (of a 

 middle-sized dog) simultaneously through apertures of an inch 

 and better in length in the intercostal spaces, will not collapse 

 the lungs, provided the animal is allowed unconfined the use of 

 his respiratory organs. 



(J, That a sound lung never fills the bag of the pleura. 



2 f2 



