416 Mr. J. F. Bullar. Experiments to Determine the [Nov. 27, 



The trachea must be kept straight, and placed so that the air can 

 freely pass in and out of it.* 



The sounds heard in the two lungs are quite different. 



Listening to the inner lung with the flexible stethoscope the breath- 

 ing sound is quite distinct, and resembles vesicular breathing, the 

 expiratory being very faint compared with the inspiratory sound. 



Altering the size of the opening of the trachea does not sensibly 

 affect this sound unless the narrowing be carried so far as to interfere 

 with the entrance of air, when the sound becomes more feeble. 



In the outer lung, in which the air is motionless, both inspiration 

 and expiration are loud, the breathing is bronchial. 



The sound is loudest over the larger bronchial tubes, but it is 

 quite distinct as far as the edges of the lung. On compressing the 

 bronchus leading to the lung the sound ceases to be heard. 



If the trachea be plugged while the inner lung is in a state of 

 inspiration and the machine kept in motion, both lungs breathe, expi- 

 ration and inspiration alternating in the two. 



The breathing sound in the outer lung now becomes " vesicular," 

 changing to bronchial whenever the trachea is opened, and it ceases 

 to breathe. The same result follows whether the trachea be left long 

 or cut off and plugged close to the bifurcation. 



These experiments show that the vesicular murmur is not pro- 

 duced in the glottis or trachea alone, since it continues when the 

 larynx and nearly the whole of the trachea are removed, and when 

 the trachea being plugged and the lungs breathing from one to the 

 other, there is no current of air through what is left of the trachea. 



With regard to the bronchial sounds in the outer non-breathing 

 lung, it is well known that a current of air passing over but not 

 entering the month of a tube produces a sound, which, under certain 

 circumstances, may become a musical note, and that in cases where 

 the sound is a noise rather than a note, that by listening carefully a 

 note may be detected through the rushing noise. This is exactly 

 the character possessed by the sound of bronchial breathing ; we 

 easily recognise, in different cases, notes of different quality and 

 pitch. 



In the non-breathing lung of the experiment, or in a case of morbid 

 consolidation, this condition is realised, the air-current passes down 



* The butchers usually remove the larynx from the trachea before the lungs are 

 sold, and in the following experiments the larynx was absent. There were three 

 reasons for my not objecting to this : 



1st. A dead larynx is a very different thing from a living one. 



2nd. The vocal cords of calves and sheep are less developed than those of man. 



3rd. A murmur is produced at the cut end of the trachea. It will be seen in the 

 sequel that the reasoning of the present paper is unaffected by the absence of the 

 larynx. 



