BEHAVIOR OF LOWER INVERTEBRATES 385 



ward, on the shell which this crab inhabits. The author dis- 

 cusses the origin and significance of the symbiotic relations of 

 these two forms. 



Buddenrock (9) finds that in Branchiomma and certain other 

 annelids that bore into the mud or sand, the statocyst does not 

 serve for the perception of jars, but affords stimuli causing the 

 side of the tail end in contact with the substratum to bend 

 downward; i.e., the statocyst is the organ of geotaxis. Extir- 

 pation of both statocysts destroys the power of boring straight 

 into the earth. 



Car (10) gives a. not very illuminating discussion of ciliary 

 movement in general and the locomotion of the ciliate infusoria; 

 he also touches upon the movements of gregarines. 



After section of the ventral cord of diplopods, Clement (11) 

 finds that co-ordinated movements between the appendages in 

 front of and behind the incision continue to occur. Stimuli 

 afforded by muscular strains are probably instrumental in 

 effecting this co-ordination. Reactions of particular appendages 

 were studied and their influence on the movements of other 

 appendages. Rolling into a spiral, which persists after decapita- 

 tion, no longer occurs if the first three metameres are removed. 



Cole (12) finds that the starfish Asterias forbesi locomotes 

 most frequently with the madrepore or one of the adjacent 

 rays in front. This ' physiological anterior " of the starfish 

 ' corresponds to the anterior of the spatangoids with respect to 

 the position of the madreporite." Starfishes tend to crawl in 

 the same general direction in successive trials, but when changes 

 of direction occur there is a tendency for the locomotor impulse 

 to " shift or rotate gradually around the body in one direction 

 or the other." 



In experiments on co-ordination and righting in the starfish, 

 Cole (13) found that individuals with the radial nerves cut near 

 the circum-oral nerve ring were nevertheless able to right them- 

 selves. The operation was accomplished only with difficulty 

 owing to the lack of co-ordinated activity in the different arms. 

 Specimens with one or more arms amputated were found to 

 right themselves as were also the individual arms. 



Cowles (14) describes the method by which Cryptodromia 

 tuber culata St., a sponge-carrying crab, snips loose a piece of 

 sponge, pushes its body under it and carries it off while holding 



