No. 4-] AMPHITHOE LONGIMANA SMITH. 181 



the animals seize bits of meat when they cannot be induced 

 to pay attention to other objects of similar appearance con- 

 vinced me that the reaction to food was caused by chemical 

 stimulation from diffusing substances in the water. 



Removal of the second pair of antennae, the first being left 

 intact, was not found to exert any marked influence upon 

 reactions to chemical stimuli. The second antennae may 

 transmit olfactory stimuli ; it would be difficult to prove they 

 do not in a certain degree, but the evidence obtained does not 

 justify us in attributing to them this function. When, after 

 removal of the first antennae, Amphithoe responds when food 

 is brought in contact with the second antennae, the reaction 

 may be due to the animal becoming aware of the presence of 

 food through some other organ, contact with the antennae 

 indicating that the food is sufficiently near to be seized. In 

 other words, the reaction may be clue to purely tactile stimula- 

 tion, the animal being keyed to this reaction by the excitement 

 of olfactory stimuli from some other organ. What other organ, 

 or organs, may serve to transmit olfactory stimuli is uncertain. 

 This has not been determined in the decapod Crustacea, which 

 afford the only other instance in which a double seat of the 

 olfactory sense has been suspected, or in fact in which, so far as 

 I am aware, any experimental evidence has been adduced as to 

 any location of this function at all. It seems probable that 

 some of the mouth parts have some olfactory function, as they 

 afford the most obviously appropriate location for such a sens'e. 

 Owing to its small size, Amphithoe is not a favorable form in 

 which to decide this question, and the attempt to do so was not 

 made. 



Color and Color Changes. 



One cannot but be struck, when examining a number of 

 specimens of this species, with the marked differences in color 

 presented by different individuals. Some are bright green, like 

 the bright green seaweeds ; others may be nearly colorless ; a 

 few are of a light blue green tint, and many range from a light 

 to a dark reddish-brown. The same individual may take on, at 

 different times, all these varieties of coloration. The color 



