534 A. MILNES MARSHALL. 



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 move- 

 ments. 



This concludes my experiments as to the afierent functions 

 of the axial cord, excepting certain points relating to the com- 

 missural connections between these cords, which will be dealt 

 with later on. I propose now to inquire into the motor func- 

 tion of the axial cords. 



Experiment 16. — As in Experiment 12, 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 sponta- 

 neously, 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 



