512 Journal of Couiparative Neurology and Psychology. 



occasioned mental action, thus indirectly favoring quickened 

 respiration. These stimuli are not comparable to the 

 meaningless pistol shots before mentioned, to which as 

 we saw, the breathing curve quickly became insensitive. 

 They are rather to be classed, though not in themselves of a 

 significant character, with the cage sounds (cooing flapping, 

 etc.). which never lost their disturbing influence upon the respir- 

 ation. For the short flashes of light probably gave the animal 

 glimpses of its prison, increased desire to escape, etc., in a word, 

 meanings, which involved heightened, rather than depressed, 

 breathing activity, and worked directly against the dulling ten- 

 dency of repetition.^ 



It is to be noticed that the normal breathing rates of the 

 four animals used in this series of tests were considerably lower 

 than those for the same birds in the preceeding series. P's aver- 

 age normal rate diminished from 23.3 to 20.9; Q's, from 24.9 

 to 23.1 ; S's, from 29.5 to 27.6; and T's, from 29.8 to 27.4. 

 This decrease was probably due to the animals' getting more 

 and more accustomed to the general conditions of the experi- 

 ment, and thus giving a less quickened, or disturbed, rate when 

 attached in the nest and before being stimulated. 



VI. Summary. 



1. The normal breathing curve in pigeons is very similar 

 to that of the human subject, except that the rate is about twice 

 as rapid. Respiration is sensitive to several kinds of stimula- 

 tion, and shows various modifications, especially quickening, 

 shallowing, deepening, pauses and irregularities of contour. 



2. Mechanical jars, sounds, and, perhaps, odors, influence 

 breathing profoundly, especially jars, often causing abrupt inhi- 

 bitions and many irregularities. 



3. Stimulation by light also disturbs the breathing, though 



^MacDougall, R. Physical Characteristic of Attention, Psychological Revieiv, 

 3, 159-180, 1896. 



BiNET et CoUR'iiER, Influence de la vie cmotionnelle sur la coeur, la 

 respiration, et la circulation capillaire, V Anncc psychologiquc, 65-126, 1896. 



