THE SYRINX OF GALLUS DOMESTICUS 195 



EXPERIMENTS ON FUNCTION 



This division of the present paper may seem almost unneces- 

 sary since Duvernoy, Girardi, Cuvier, and others of the older 

 investigators conclusively demonstrated that voice is produced 

 in the lower larynx. Kitchner ('85), and other observers, how- 

 ever, have expressed their doubts concerning the correctness of 

 the conclusions arrived at by these early investigators. Because 

 of such doubts it was thought best to include these experiments. 



Experiment I. The trachea of an adult cock was divided at its 

 middle, after which the bird was set free with others. After the 

 operation crowing occurred quite frequently, but the voice was 

 somewhat modified. In order to study these modifications more 

 carefully, phonographic records were made of the crowing before 

 and after cutting the trachea. These records were made in the 

 folloAving manner. A normal adult cock was placed in a small 

 room. After becoming accustomed to the new environment he 

 had periods of crowing which were quite regular. An Edison 

 phonograph was arranged just outside, so that the horn projected 

 into the room through a small opening. This allowed the experi- 

 menter to operate the machine unseen. The early morning hours 

 were found best for making records, as crowing was more fre- 

 quent and regular at that time. 



It is interesting to note that such birds usually crow about five 

 or six times at intervals varying from ten to fifty seconds, then 

 after an interval of fifteen minutes to one hour, they again begin 

 to crow. 



After a sufficient number of records had been made, the bird 

 was deeply anaesthetised and a small part of the trachea exposed 

 (fig. 17). This caused no noticeable difference in the voice. 

 After sufficient recovery the trachea was treated with a local 

 anaesthetic and cut entirely across. The cephalic end was tied 

 tightly so there was no possible chance for air to pass from it 

 through the upper larynx and the mouth. The caudal end was 

 left open and allowed to protrude through the skin of the neck 

 (fig. 18). The operation had no marked effect on the well-being 

 of the bird, for, not more than two hours later this same cock. 



