ANIMAL PSYCHOLOGY IN FRANCE 451 



changed at once. As soon as a crab encountered a shell he 

 carried it off, and for five or ten minutes persistently explored 

 it in all directions and tried to pull off the cork. This fact proves 

 not only that new associations can be formed in these crabs, and 

 that consequently they are susceptible of training, but also that 

 they are capable of apprehending form differences by means of 

 tactile sensations. 



Two important memoirs relating to the experimental analysis 

 of instincts, by Faurot and by Cornetz, have appeared. — 



Faurot " first studies the adaptive conformation of the hermit 

 crab and the deformity and growth of Adamsia palliata in sym- 

 biosis with Eupagurus Prideauxi. The development of the 

 actinian forms in a certain sense part of that of the crab. The 

 association of Pagurus striatus and Sagartia parasitica presents 

 quite different features ; it does not begin until the two organisms 

 have almost reached their normal growth, and it is always pos- 

 sible for them to live separated from each other. F. investigates 

 the mode of formation of the two sorts of association; symbiosis 

 and mutualism. He brought together naked Eupagurus Pri- 

 deauxi, others lodged in shells furnished with Adamsias, empty 

 shells with Adamsias on them, and Adamsias either isolated 

 from their shells or adherent to some support. In general the 

 crabs recognized the Adamsias by means of their tactile sensi- 

 bility, which is extraordinarily developed; they immediately 

 carried off' an Adamsia palliata, hut not Sagartia parasitica, 

 Heliactis bellis, or Corynactis viridis. Crabs provided with 

 Adamsias, put near naked shells, did not exchange their shelter 

 for the latter. If they were despoiled of their associates, they 

 fell upon a naked shell with as much eagerness as if it had been 

 an Adamsia. If, however, the separation were of less recent 

 date,- the attracting reaction produced by contact with a naked 

 shell was much weaker. In the search for shells and actinians 

 sight plays a certain role; the visual field would be bounded by 

 a regular circle whose radius is the length of the antennae plus 

 four to six centimeters. 



F. describes a Pagurus striatus detaching a Sagartia parasitica 

 from the bottom of the aquarium: the claws of the crab grasp 

 the actinian especially in the region near the edges of the pedal 

 disk. This region gradually diminishes in diameter and the disk 

 detaches itself from the support; the tentacles of the actinian 



