364 LEON J. COLE. 



Here the muscular pull of the forward part acts as the stimulus 

 for contraction in the posterior piece. Loeb's experiment in this 

 connection was negative. He cut the nerve ring of a starfish 

 at two points, nearly opposite to each other, thus severing the 

 nervous connection of certain arms with the others. He found 

 that whereas "the normal starfish requires but a few minutes 

 to turn over, . . . the specimen [operated upon as described] 

 remained on its back the whole afternoon, although the arms 

 were struggling constantly to right it" (Loeb, 'oo, p. 63). Ro- 

 manes ('85, p. 296) had, however, previously obtained different 

 results in his experiments on the common British starfish. He 

 states that when animals with the radial nerves severed at the 

 bases of the arms are inverted, "the power of effecting the righting 

 manoeuvre is seen to be gravely impaired, although eventually 

 success is always achieved." My experiments on Asterias forbesi 

 agree in this respect with those of Romanes. 



Experiment I. (Specimen No. 10 of earlier paper.) In three 

 preliminary trials this specimen required 6 minutes, 5 minutes 

 and 6 minutes respectively for righting, and turned on arms cd, 1 

 be and cd in the successive trials. An incision was now made at 

 the base of each arm, thus severing the radial nerves (and of 

 course the radial water canals as well) close to their origin from 

 the circumoral ring. The specimen was again placed on its 

 back in the water, and the various arms at once began to make 

 individual and apparently random movements toward righting. 2 

 While most of the arms went through various activities, bending 

 and twisting, attaching and pulling, only to let go again, arm c 

 persisted only in bending up orally, and did not twist and attach. 

 This resulted finally, at the end of 20 minutes, in its becoming 

 bent over far enough to obtain a hold between a and e, as shown 

 in Fig. i A. Arms b and d were also thrown well over at the 



1 Following Jennings ('07) the arms are designated a, b, c, d and e, beginning at 

 the ray to the right of the madreporite and going around clockwise (cf. Cole, '13, 

 p. 2). Dr. R. T. Jackson has emphasized (in lilt.) the desirabilty of students of 

 animal behavior, as well as specialists, using for the starfish the nomenclature in- 

 troduced by Loven for the ambulacral and inter-ambulcral areas of Echini. With 

 this view I am in accord and should have adopted the method had it not been that 

 my earlier paper necessitated so much direct comparison with that of Jennings, 

 and a different nomenclature would have made such comparison difficult. 



2 If there is any shock from the operation, it is so slight as to be hardly noticeable. 



