ACQUIRED SPECIFIC REACTIONS TO COLOR 167 



left, side. Eight reactions were thus obtained, in which the 

 animal was given the opportunity to react either to the color 

 to which it had been exposed or to another. Although one 

 color was thus exposed 4 times to once of each of the other 

 colors, it is the author's opinion that the results are not vitiated 

 by this procedure. Evidence for this position is furnished by 

 the reactions of Specimen 16, from which a complete series of 

 20 observations was obtained. Although this individual was 

 exposed to the action of red light for 24 hours prior to the 

 reactions, a marked chromo-kinetic-resonance is apparent which 

 is not altered in any way by the subsequent reactions to the 

 other lights. It seems reasonably certain therefore that had a 

 full series of twenty reactions been obtained from each of the 

 other specimens which had been exposed to a certain light, 

 the results would not have been different from those actually 

 obtained. Furthermore, as appears from Table I, which shows 

 the order in which the lights were presented, in the experiments 

 recorded in Table II red was shown 8 times, yellow 6 times, 

 green 4 times and blue 2 times in succession. Yet in spite of 

 the inequality in the order of presentation, there is no evidence 

 whatsoever that the light which was exposed most often in 

 succession, received most reactions. In fact red which heads 

 the list in this respect, was reacted to least frequently. The 

 results which follow, therefore, can not be explained upon the 

 assumption of an undue influence of the color from the fre- 

 quency of its successive presentation. 



The aquaria in which the crabs used in this series were exposed 

 to colored light for 24 hours prior to testing their reactions in 

 the manner just described, were made by painting the insides 

 and bottoms of galvanized iron pails. The diameter of the top 

 was 250 mm. that of the bottom 212 mm. The depth of the 

 pails was 250 mm. The area of the sides and bottom is equal 

 to 2063.85 sq. cms. The color of the paints can not be char- 

 acterized very definitely. The red was a vermilion; the blue 

 an ultramarine; the green a "dark" green; the yellow a 

 "lemon" yellow. The aquaria were suspended in the large 

 aquarium already described, in such a manner that their tops 

 were about 3 cms. under the surface of the water. In this way, 

 a supply of fresh water was secured. The observations in the 

 reaction box were made immediately after taking the animals 



