Bell, Reactions of Crayfish. 301 



Bateson ^ says that prawns and shrimps when blinded find 

 pieces of food quite as quickly as when uninjured. Shrimps find 

 their food more quickly than prawns. They hunt with their heads 

 down like hounds, whereas prawns hunt with their heads up as 

 usual. If a worm is just buried in the sand the shrimp will dig 

 it out whether blinded or not. If worms are put into one tank and 

 the water allowed to flow into another where the shrimps are, 

 they become very restless and hunt about for the food. If a 

 worm be hung in water about eight inches from the bottom, prawns 

 will first hunt about on the bottom, but on coming directly under 

 the booty they will rise to it at once. 



Nagel^ has performed some very interesting experiments on 

 Crustacea. The reactions of Pagurus, Astacus and Carcinus to 

 chemical stimuli were observed, and the opinion is expressed 

 that the chemical sense is not of as much value as sight and touch 

 in localizing food. A blinded Pagurus was very much excited 

 by meat but could not find it even when it was close to him. If 

 the animal chanced to touch it the meat was seized at once. There 

 seemed to be evidence that the antennules were the most sensi- 

 tive to chemical stimuli, but when these were destroyed the re- 

 actions, though reduced, were by no means eliminated. 



Astacus reacted to bits of Limburger cheese by moving their 

 antennae and antennules slightly and waving the filamentous 

 endopodites of the maxillipedes vigorously. One would suppose 

 that the latter might carry chemical sense organs, judging from 

 the reaction, but this is not the case, for all the hairs are plumed 

 and none have an opening at the base to admit the nerve. The 

 animals would go to the cheese, touch it with their chelipedes, 

 and then leave it without eating. Saccharine caused movements 

 of the antennules different from anything ever observed under 

 other conditions. Lavender water and i percent, and 2 per cent, 

 solutions of hydrochloric acid caused reactions which were inter- 

 preted as disagreeable. The former caused the antennules to be 

 stuck down toward the mouth parts, while the acid made the 

 animal wipe its antennules, then its antennae, and finally but 



'Bateson, W. Notes on the Senses and Habits of some Crustacea. Journal Marine Biological 

 Association {Plymouth), Yo\. i (N. S. ), pp. 211-214. 1889. 



^Nagel, W. a. Geruchs- und Geschmackssinn. Bibliotheca Zoologica, Leuckart und Chun, Vol. 

 18, pp. 1-207. 1894. 



