414 Mr. J. F. Bullar. Experiment* to Determine the [Nov. i'7. 



The frame (fig. 3) was screwed down air-tight upon a ring of india- 

 rubber tube placed round the hole in the roof of the chamber A, and 

 the interval between the left bronchus and the frame stopped up 

 by wrapping some tow, dipped in a strong solution of gelatine, round 

 the bronchus. 



The whole chamber containing the lung was now air-tight, and by 

 opening the upper tap I and raising the handle of the bellows, any 

 air remaining above the water in the chamber or any superfluous 

 water could be expelled. 



When the tap I was shut, moving the handle up and down caused 

 the lung within the chamber to breathe, and by fixing the handle in 

 different positions the lung could be kept motionless at different 

 degrees of distension. 



The chamber thus represented a thorax in which there was a 

 sufficient amount of fluid to separate the surfaces of the lung and 

 chest wall, and in which the respiratory movements were entirely 

 diaphragmatic. 



The motion of the machine itself and of the water contained in it 

 produced no sound. 



The object and results of the experiments about to be described 

 will be made clearer by introducing here a short account of the 

 respiratory sounds, and as the changes in the sounds produced by 

 alterations in the physical condition of the langs throw light upon 

 their origin, a short account of the more important of these changes 

 is also necessary. 



The sounds to be considered may be divided into those of speech 

 and those of respiration. 



A. The sounds of speech are produced in the mouth and larynx. 

 They are heard loudly and distinctly by the stethoscope over the 

 larynx and trachea ; over the parts of the chest in contact with the 

 vesicular structure of the lungs they are weaker and indistinct. 



In the neighbourhood of the large air passages, e.g., in the inter- 

 scapular space, the sounds are less weak and indistinct than at other 

 parts of the chest, and approach more nearly in character to the 

 sounds heard over the trachea. 



B. The origin of the respiratory sounds is a disputed point. 



Over the trachea during both inspiration and expiration a rushing 

 sound is heard. 



Over the lungs a sound is heard during inspiration of a different 

 character from the tracheal inspiratory sound, and during expiration 

 the sound is either very faint or altogether absent. 



As in the case of the voice there may be, in the neighbourhood of 

 the large air passages, an approximation to the tracheal sounds. 



The sounds heard over the lungs are known as the sounds of 

 " vesicular breathing." 



