MALE DOVES REARED IN ISOLATION 133 



style, whereas the same act after much experience is performed 

 with ease, skill, and intelligent adaptation. Thus even those 

 acts which do not show improvement by the formation of asso- 

 ciations, show improvement by facilitation. 



10. In "the case of an act in which instinct plays the greater 

 part, and learning by experience the lesser part, especially when 

 the result of experience is merely facilitation, the improvement 

 in the performance of the act may be so rapid that it quickly 

 leads to perfection. To detect the influence of experience or 

 practice, one must observe from the very first performance of 

 the act. To observe the very first performance of the social 

 activities of the adult, one must rear the animal in isolation; 

 and then allow it, while under close observation, to come into 

 contact with another animal. 



