472 S. O. MAST 



INTRODUCTION 



But little interest was manifested in the response of animals 

 to colors until some time after the appearance of the Origin of 

 Species (1849). This work at once greatly stimulated research 

 in comparative morphology and embryology, with the result 

 that there was soon collected a mass of material in support of 

 the theory of evolution in so far as it pertains to the structure 

 of organisms. In connection with this work on the origin of 

 structure there continually arose problems concerning the evo- 

 lution of functions, reactions, behavior, consciousness, etc. 

 Among these was the question as to the relation between color 

 and stimulation. This question was associated with the prob- 

 lem of evolution of psychic phenomena, and that of the evolu- 

 tion of color-patterns in animals and plants especially those in 

 the flowers. 



As apphed to color-patterns in animals, the theory of evolu- 

 tion demanded color-vision on the part of the animals involved, 

 for the patterns were considered to be associated with concealing 

 phenomena and sexual selection; and as applied to flowers it de- 

 manded color-vision in those insects which have to do with pol- 

 lination, for it was assumed that color is a determining factor 

 in attracting insects and consequently that the reproduction of 

 a plant depends upon the color of its flowers. But these ideas 

 did not result in as much experimental work on the response of 

 animals to colors as did the problem of the evolution of psychic 

 phenomena. 



It was at this time maintained that if psychic phenomena 

 originated by the process of evolution, one ought to find evi- 

 dence of mental faculties in the lower organisms.' And there 

 soon appeared a group of investigators who took up the study 

 of the behavior of animals primarily in search of just such 

 evidence. Prominent among these may be mentioned Bert ('69), 

 Darwin ('80), Lubbock ('81), Romanes ('83), Graber ('83) and 

 Preyer ('86). In general, the results obtained by the men just 

 mentioned led them to conclude that psychic phenomena extend 

 well down in the scale of animal life, if not to the very bottom. 



