196 JAY ARTHUR MYERS 



when placed with some other chickens, was eating and crowing 

 as though nothing had happened. Records of the crowing were 

 made on the following morning. These records were preserve^ 

 and carefully compared "with those taken before the operation. 

 This comparison showed that after the trachea had been cut, 

 tones were produced as before but the pitch was noticeably higher. 

 It must be admitted, therefore, that the trachea and upper larynx 

 serve to modulate voice, just as the pharynx and cavities in the 

 mouth serve the same function in mammals. 



Similar experiments were performed on the domestic duck with 

 precisely the same results. 



Through the kindness of Dr. Max Meyer, professor in experi- 

 mental psychology, University of Missouri, the author is able 

 to give here the exact changes in pitch which result from divid- 

 ing the trachea. Dr. Meyer determined the pitch of the voice of 

 a normal adult male. In this particular individual he found the 

 normal tone was one of about 375 double vibrations per second. 

 The pitch is constant from time to time. It is interesting to 

 note that there is also but little difference in the pitch from the 

 beginning to the end of crowing. It was observed, however, 

 that the pitch is slightly higher at the beginning, there being 

 a fall of not more than twelve double vibrations. 



After the trachea was divided the number of double vibrations 

 was increased to about 500 per second. 



The voice in crowing is not interrupted, but is produced by 

 one continuous flow of air causing vibrations of the tympanic 

 membranes. Ordinarily a single crow lasts for about three or 

 four seconds. But in one individual it was observed that after 

 the trachea was divided crowing extended over scarcely a single 

 second of time. As explained by Dr. Meyer, there are two pos- 

 sible reasons for the time of crowing being so much reduced. 

 First, when the neck is stretched pain may result from the wound. 

 Second, the tone produced is so unnatural that it is soon 

 discontinued. 



Experiment II. Since the lungs of birds are not elastic struc- 

 tures as in mammals, but are more solid, it is obvious that other 

 organs with a large air capacity must be present, and further, 



