Organic Connection Between Physical and Psychical 279 



science generally is practiced, and experimentation in one 

 form or another is employed as a supplementary agency 

 wherever and whenever possible. One of the best examples 

 of this type of zoological research and writing is Ants, by 

 W. M. Wheeler. But a considerable portion, and fortunate- 

 ly an increasing portion, of experimental research in animal 

 behavior is being done quite in the spirit of field zoology. 

 The work of R. M. Yerkes deserves mention as perhaps the 

 most definitely purposed and executed combination of the 

 field and experimental methods for investigating the behavior 

 of mammals and birds, that has yet been made. But much 

 of the research recently named animal ecology tends strong- 

 ly toward rigor in field investigation. This kind of study is 

 specially adapted to bring out the specific nature of behav- 

 ior, since the group of organisms, species, etc., as a whole, 

 occupies a central place in the student's interest, so that if 

 behavior is attended to at all its differential features are 

 likely to receive attention along with the differential struc- 

 tural features. 



(2) Laboratory experimentation on animal behavior has, 

 as previously indicated, been prosecuted more intensely and 

 widely in the modern period than either of the other classes 

 of investigation. In fact, it may be said to be distinctive of 

 the period, and to have set the standard as regards rigor for 

 the other types of investigation. From its very nature, how- 

 ever, it is not calculated to bring the specificity of behavior 

 to a central place in the student's interest. Singling out 

 as it does one or a few attributes at a time as they are ex- 

 hibited by one or a few individuals of one or a few species, 

 breadth and penetration of comparison are liable to be sacri- 

 ficed. This kind of research tends to be extremely particu- 

 laristic in every way. Nevertheless, painstaking and judi- 

 cious workers, like Englemann, Forel, Binet, Wasmann, 

 Romanes, C. Lloyd Morgan, Verworn, Jennings, Loeb, 

 Holmes, and Parker, generally state what species their in- 



