Introduction. 



XIX 



tion of their subjects, and these are preferable to poor photographs, but for the study of 

 animal behavior in both the invertebrates and vertebrates the camera is immeasurably 

 superior to brush or pencil. Popular natural history books have already a large body of 

 invaluable material to draw upon for illustrative purposes, and the often crude, impossi- 

 ble, or imperfect drawings, which have so long done service in the past, will gradually 

 give place to truthful delineations of animals at home, and in the midst of that nature of 

 which they form a part. 



