THE NERVOUS SYSTEM OP ANTEDON ROSACEUS. 271 



arms of Actinometra the cord enlarges in the centre of each ossicle 

 and gives off branches to both dorsal and ventral surfaces, some of 

 the latter reaching " the bases, or in some cases even the tips of the 

 respiratory leaves." He even suspected a connection between some 

 of those branches of the axial cord and the subepithelial bands ; some, 

 he says, " appear to enter into the plexus of tissue forming the organic 

 base of the skeleton, others seem to become connected with epidermic 

 structures." 



In a supplemental note 1 Dr. Carpenter also confirms the existence 

 of the subepithelial band, and considers that it is " by no means im- 

 probable, looking alike to its position and to its histological character, 

 that this band is a nerve." On account mainly of its position he 

 suggests that it is " an afferent rather than a motor nerve." He also 

 brings forward the following extremely important additional experi- 

 mental evidence in support of the nervous nature of the central capsule 

 and axial cords. 



Experiment B. — The visceral mass was removed from a large and 

 vigorous Antedon, leaving the calyx with the central capsule and the 

 arms intact. On replacing the animal in the water it executed the usual 

 swimming movements as perfectly as the entire animal had previously done. 

 Experiment G. — From a second active specimen the entire centro- 

 dorsal basin with its contents and appendages were removed. On 

 replacing the animal in the water all the arms were rigidly straightened 

 out, apparently by the action of the elastic ligaments which the muscles 

 were powerless to antagonise. 



Experiment B. — In an active specimen the soft parts of one of the 

 arms were divided down to the calcareous segments. On replacing 

 the animal in water all the arms worked as usual without the slightest 

 disturbance of regularity. 



Experiment E. — By means of nitric acid applied with a fine brush, 

 the dorsal half of one of the arms was dissolved away until the axial 

 cord was reached and destroyed. On replacing the animal in the 

 water the injured arm remained rigidly stretched out, while all the other 

 arms worked as usual. 



From these experiments Dr. Carpenter concludes that the central 

 capsule is the co-ordinating centre of a nervous system whose peripheral 

 portion consists of the axial cords of the rays, arms and pinnules; also 



1 Carpenter, ' Proceedings of the Royal Society,' vol. xxiv, 1876, p. 651. 



