Rouse, Respiration in Pigeons. 497 



Acoustical, olfactory, mechanical and visual reactions 

 were studied. Pistol shots of two intensities and the 

 ringing of an electric bell, were used as acoustical stimuli. 

 Turpentine, ammonia, asafoetida, oil of bergamot and lily of the 

 valley were employed as odors, and were given in small paper 

 pans, placed on a smoothly moving wooden drawer which fitted 

 into the front of the box that covered the bird. Jars were util- 

 ized as mechanical stimuli. As visual stimuli red, yellow, green 

 and blue lights were used. These were obtained by use of 

 incandescent lamps, and colored glasses, placed vertically on 

 either side of the animal. Equality of intensity for the different 

 colors was maintained by altering the distance of the source of 

 illumination from color to color. Different intensities were 

 secured by changing lamps. 



The time of giving the various stimuli was usually indicat- 

 ed automatically by an electrical signal marker, writing just below 

 the respiration tracing. This was made possible in the case of 

 visual tests, for example, by the use of a double contact key. 

 Rate of drum movement was shown in a third line below, writ- 

 ten by a marker which was connected with a metronome. The 

 instrument beat half seconds, and was enclosed in a heavy, felt- 

 lined box. 



II. Normal Respiration. 



The general contour of the pigeon's normal breathing 

 curve (see Fig. 2) is quite similar to that of man, although the 

 rhythm is much more rapid. ^ The inspiration, or active part 

 of the respiratory act, is usually shorter and more regular in 

 outline than the expiration, or passive part. It begins rapidly, 

 but commences to slacken a little before the middle of its course, 

 and shows a slight pause at the end. The expiration also soon 

 begins to decrease in rate, but the diminution is generally more 

 gradual, and the pause at the end is longer. 



In order to determine the relative duration of inspiration 



'Starling, op. cit. 



