BEHAVIOR OF LOWER INVERTEBRATES 399 



showed no evidence of learning to use a certain arm, but they 

 could be compelled to use certain arms by injuriously irritating 

 the others. 



Experiments were carried on by Morse '^ with Littorina litorea, 

 Littorina rudis, and Ilyanassa obsoleta, in order to test the con- 

 clusion of Bohn that the two former species show periodic changes 

 of phototaxis synchronous with the rise and fall of the tides. 

 Although the sense of the response showed certain daily changes 

 and certain modifications of a longer interval, there were no 

 changes observed which corresponded with the rhythm of the 

 tides. 



Parker's paper " contains a record of the first serious at- 

 tempt to study the behavior of sponges in detail. While a 

 sponge is capable of performing only a very few inconspicuous 

 acts, its behavior is of especial interest on account of the ab- 

 sence of a definite nervous system. The oscula or excurrent 

 openings slowly close on exposure to air, or w^hen subjected 

 to injurious mechanical stimulation, or to stimulation by chem- 

 icals. The currents produced by the collared cells set only in 

 one direction; they become slow at a low temperature, but they 

 are at first accelerated in water deprived of oxygen, although 

 they afterward became slower and finally cease. The ostia 

 or incurrent orifices close in solutions of ether, strychnine, 

 and chloroform, but open in warm or deoxygenated sea water 

 and in certain solutions of chemicals. They are comparatively 

 unaffected by mechanical stimuli. Injuries have no effect on 

 the ostia or oscula unless when very close to them. Trans- 

 mission of impulses occurs only over very short distances, and 

 there seems to be little or no coordination between the action 

 of the various parts. The final section of the paper contains 

 a discussion of the origin of the nervous system. 



Polimanti ^^ describes some experiments in which hermit 

 crabs bearing the anemone Adamsia were placed in an aquarium 

 with the cephalopod Eledone moschata. Although the Eledones 

 repeatedly came in contact with the anemones and as often 

 recoiled from the sting of the nettling cells, they gave no evi- 

 dence of learning to avoid the irritating objects. The author 

 concludes that memory in these cephalopods is very feeble, 

 if it exists at all. 



