:.l6 BIOLOGICAL LECTURES. 



into a permanent instinct"? To suppose that such jitterly 

 useless action originated a great many times without compelling 

 conditions or any organic predisposition is not at all admissible. 

 Darwin saw at once from the nature of the actions that they 

 could not have been taught, but '' must have appeared naturally, 

 though probably afterwards vastly improved by the continued 

 selection of those birds which showed the strongest propensity y 

 Darwin, then, postulates as the foundation of each instinct a 

 "propensity" — something given in the constitution. That 

 view of the matter is in entire accord with the theory adopted 

 in the case of neuter insects and quite incompatible with the 

 habit theory. 



1. The Instinct of Pouting. — I believe the case is much 

 stronger than Darwin suspected, and that it shows, not the 

 genesis of instinct from habit, but from a preexisting congen- 

 ital basis. Such a basis of the pouting instinct exists in every 

 dovecot pigeon, and is already an organized instinct, differing 

 from the instinct displayed in the typical pouter only in degree. 

 I could show that the same instinct is widely spread, if not 

 universal, among pigeons. It will suffice here to call attention 

 to the instinct as exhibited in the common pigeon. Observe 

 a male pigeon while cooing to his mate or his neighbors. 

 Notice that he inflates his throat and crop, and that this 

 feature is an invariable feature in the act, often continued for 

 some moments after the cooing ceases. Compare the pouter 

 and notice how he increases the inflation whenever he begins 

 cooing. The pouter's behavior is nothing but the universal 

 instinct enormously exaggerated, as any attentive observer may 

 readily see under favorable circumstances. 



2. The Insti7ict of Tumbling. — The origin of the tumbling 

 instinct cannot be fixed by the same direct mode of identi- 

 fication ; but I believe that here also it is possible to point 

 to a more general action, instinctively performed by the dove- 

 cot pigeon, as the probable source of origin. I have noticed 

 a great many times that common pigeons, when on the point 

 of being overtaken and seized by a hawk, suddenly flirt them- 

 selves directly downward in a manner suggestive of tumbling, 

 and thus elude the hawk's swoop. The hawk is carried on by 



