498 Journal of Comparative Neurology and Psychology. 



and expiration, I measured the ten most regular consecutive 

 respirations which appeared in the daily record of the normal 

 breathing movements of one bird. Following are the ratios for 

 thirty-two days, stated as expiration to inspiration: — 1.50:1, 

 1.28:1, 1.13:1, 1.04:1, [.50:1, 1.25:1, 1.55:1, 1-33:1. 1-30:1, 

 1.22:1, 1.08:1, 1.55:1, 1.46:1, 1.20:1, i.ii:i, 1.82:1, 1.31:1, 

 1. 18:1, 1.23:1, 1.05:1, 1.38:1, i.ii:i, 1.30:1, 1.21:1, 1.13:1, 

 1.13:1, 1.22:1, 1.33:1, 1.38:1, 1.18:1, 1.05:1, 1.21:1. Gener- 

 al average = 1.27:1. This is very nearly the ratio found to 

 obtain in human breathing, or 1.20:1. It will be seen that 

 each day the expiration was longer than the inspiration, though 

 the preponderance varied from day to day. 



Some of the days on which records were taken were 

 not consecutive, and it was found that an intermission usually 

 resulted in a considerably increased lengthening of expir- 



Fig. 2. Normal breathing curve. A single respiratory act extends from 

 hollow to hollow. The left hand, or shorter, part is the inspiration. The line 

 is here made too heavy to show minute variations. 



ation, although this advance generally disappeared in the 

 next few consecutive days. The ratio for March 22, for exam- 

 ple, was 1.08:1, but for the next four tests (March 25, 26, 28 

 and 29) it was, respectively, 1.55:1, 1.46:1, 1.20:1, i.ii:i. 

 After a still longer intermission the ratio showed a still greater 

 change, rising to 1.82:1, but rapidly losing again during the 

 next few consecutive days as follows: 1.31:1, 1.18:1, 1.23:1, 

 1.05:1. The decrease of ratio was probably due to the fact 

 that there was a tendency for the animal to become gradually 

 accustomed to the general situation on the consecutive days, 



