NERVOUS system; of antedon eosaceus. 523 



arm -vnll retain its vitality for many hours. It will at first 

 exhibit strong movements of flexion, lasting from a few 

 minutes to as long as a couple of hours, the arm being alter- 

 nately coiled up spirally, and then extended with great force 

 and rapidity. 



Antedon, if kept in captiA-ity, requires the water to be fre- 

 quently changed, or else very efficiently aerated. Specimens 

 left over-night in a small basin of sea-water were found dead 

 the next morning. In dead specimens, owing to the unopposed 

 action of the elastic ligaments, the arms are very strongly 

 extended. 



B. On the Effects ofRemoval ofthe Visceral Mass. 



In a living specimen the visceral mass can be removed from 

 the calyx with great ease, as was pointed out long ago by Dr. 

 Carpenter. If the visceral mass be grasped with forceps an 

 exceedingly slight pull suffices to remove it. In such evis- 

 cerated specimens the central capsule with its prolongations 

 and the axial cords remain in the calyx intact, excepting, of 

 course, the branches of the cords described by P. H. Carpenter 

 as distributed to the oral perisome; the ambulacral grooves 

 and other soft parts, on the other hand, are torn across at the 

 bases of the arms, and the subepithelial bands consequently 

 isolated from one another. 



Experiment 1.^ — A large and vigorous specimen was 

 eviscerated without removal from the water. On being re- 

 leased it remained quiescent for about a minute, and then 

 swam about the tank actively and in a perfectly normal 

 manner. After a short time it came to rest on the bottom in 

 a perfectly normal position. Half an hour later, without the 

 slightest disturbance or irritation of any kind, it began spon- 

 taneously to swim agaiu actively and normally. Coming in 



' For convenience of reference I propose to number the various experiments 

 consecutively. It will be understood that they were not made in the order 

 given here, and that only those which seem of distinct importance are recorded. 

 Ko experiment is described from a single observation only, and in most cases 

 the experiments were repeated several times. 



