THE NERVOUS SYSTEM OP ANTEDON ROSACEUS. 285 



The stump was carefully dried and the axial cord touched with a 

 fine needle or with a finely-pointed brush charged with nitric acid, 

 very violent movements of all the arms at once resulting. Similar 

 stimulation of the ambulacral epithelium or of other parts of the 

 section produced but very slight and local movements. 



This concludes my experiments as to the afferent functions of the 

 axial cord, excepting certain points relating to the commissural 

 connections between these cords, which will be dealt with later on. 

 I propose now to enquire mto the motor function of the axial cords. 



Experiment 1 6. — As in Experiment 1 2, the soft parts were scraped 

 away from the ventral surface of about a quarter of an inch of one of 

 the arms, an inch from its base. On being returned to the water the 

 animal swam actively, all the arms moving vigorously and normally, 

 including the injured one, which, however, was rather less active than 

 the others, and a little stiff at the scraped part, probably from direct 

 injury to the muscles. 



This experiment, which was repeated on eviscerated specimens with 

 identical results, shows that the path by which motor impulses are 

 conveyed to the muscles of the arms is neither the subepithelial band 

 nor any part of the soft structures on the ventral surface of the arm. 



Experiment 17. — The operation was the same as in Experiment 14, 

 the dorsal half of one of the arms, about an inch from the disc, being- 

 dissolved away by nitric acid until the axial cord was exposed and 

 divided. The animal was then returned to the water, where it remained 

 quiescent for a few seconds, and then commenced to swim actively and 

 spontaneously, all the arms moving perfectly normally, except the 

 injured one, the proximal end of which moved slightly, while the distal 

 part beyond the injury was perfectly motionless and flexed spirally 

 into a coil. After a short time the animal came to rest in a perfectly 

 normal position, but for the spiral coiling of the distal part of the 

 injured arm, which persisted. After a quarter of an hour's rest one of 

 the uninjured arms was irritated, causing at once active movements 

 of the uninjured arms and of the proximal part of the injured arm, 

 but none whatever of its distal part. 



Experiment 18. — In a fresh Antedon tw r o injuries, similar to that in 

 Experiment 17, were made in one of the arms at spots about an inch 

 and a half apart. Stimulation of the arm itself, or of the pinnules, 

 between the two wounds caused movements of the middle portion of 

 the arm, but none whatever of the proximal or distal portions. 



