ACQUIRED SPECIFIC REACTIONS TO COLOR 177 



sumed to be dependent upon a specific modification of the 

 light receptor organs and the ner^e cells connected with them, 

 which determines the kind of stimulus to which a crab pos- 

 sessing such a "resonance" can respond. 



2. Blinded crabs decorate themselves as do normal crabs 

 both as regards the mode of operation and the result. 



3. Blinded crabs do not react to light stimuli. These latter 

 results taken together show beyond doubt that some other 

 than the visual stimulus may excite the decorating response. 

 This other stimulus may be assumed to be tactile. The results, 

 however, leave in doubt the question whether visual stimuli 

 alone may excite the decorating response. 



The results just stated are the only experimentally deter- 

 mined conclusions which may be drawn from our work. And 

 the problem stated at the outset of the paper " By the action 

 of what stimuli and by the execution of what responses is the 

 decoration carried out" must remain unsolved for the present. 

 Of the three possibilities enumerated on page 176 only two, 

 namely, the second and the third can be definitely disposed 

 of. The three possibilities were: 



i. Visual stimuli alone may initiate the response, 

 ii. Tactile stimuli alone may initiate the response. 

 iii. Visual and tactile stimuli together may initiate the response. 



Whether visual stimuli alone can initiate the response remains 

 undetermined by our experiments. It might seem from the 

 existence of a specific, acquired, chromotropism that visual 

 stimuli may certainly excite the instinct in question. Such an 

 assumption is actually made by Minkiewicz. But a moment's 

 reflection will show that all that the chromo -kinetic resonance 

 does is to move the crab fatally towards a source of light of 

 the same quality as that to which it has been exposed. It is 

 quite conceivable that such an acquired chromotropism has 

 nothing whatsoever to do with the decorating instinct. Indeed 

 it is only the belief that a "harmony" existed between costume 

 and color environment that has jutified the assumption. Whether 

 a crab deprived of tactile receptors yet possessing light receptors 

 and impressed with a chromo-kinetic resonance would decorate 

 itself when placed in the presence of suitable material is an 

 unsolved problem. The writer is of the opinion that such an 



