Bell, Reactions of Crayfish. 319 



It was not expected that the animal would survive, but it remained 

 as active as ever, and was still alive when the whole lot was dis- 

 posed of four months after the trial. 



5. Saturated Salt Solution. — After the preceding experiments 

 had been performed it was thought that it might be of interest to 

 observe the reactions of the crayfish to substances which on the 

 human tongue give the three other principal tastes, salt, sweet, 

 and bitter. For the first a saturated solution of common salt was 

 used, and five animals were experimented on as before, (i) Stim- 

 ulation of the antennae caused a quick movement of those organs 

 and a general restlessness of the animal, accompanied in one case 

 by a grasping with the chelipedes. (2) In every case the forceps 

 of the chelae were opened or closed, and the member was with- 

 drawn. The animals became restless and moved away from the 

 stimulus. One even stuck up its chelae in the attitude of attack. 

 (3) When the antennules were stimulated the animals grew rest- 

 less, moved away, and invariably thrust the antennules down and 

 wiped them with the maxillipedes. Only the member stimulated 

 was lowered, never both at once. In one case there was grasping 

 with the chela. (4) All the animals responded to stimulation of 

 the mouth parts with restlessness, movement away from the stim- 

 ulus, chewing movements in all cases but one, grasping with the 

 chelipedes in two cases, and bringing them to the mouth in four. 

 (5) The first chelipedes closed with a snap in four cases and were 

 brought to the mouth in three. In all cases there was great rest- 

 lessness and movement away from the stimulus. One animal 

 rubbed the cheliped stimulated with the opposite one and with the 

 second chelipedes. (6) Stimulation of the second chelipedes also 

 caused decided restlessness and withdrawal from the stimulus in 

 all cases. In three cases there was grasping with the member 

 affected, and in one there was vigorous spreading of the forceps 

 and rubbing with the other members. (7 and 8) On the third and 

 fourth chelipedes the chief reactions were slight movement and 

 increased restlessness. In two cases the first chelipedes were 

 brought to the mouth, and in two the member stimulated was 

 rubbed by others. In one case on stimulation of the right third 

 cheliped the whole ventral surface was vigorously rubbed by the 

 second, third and fourth chelipedes, then the right third was 

 rubbed by the left fourth reaching under, and finally the member 

 stimulated was thrust up to scratch the dorsal portion of the cara- 



