656 



PROCEEDINGS OF THE AMERICAN ACADEMY. 



system does not exert any appreciable influence upon the process of 

 regeneration. 



While working at the Bermuda Biological Station for Research last 

 summer, I undertook a study of some phases of this problem on the 

 brittle-star Ophiocoma pumila with a view to determining certain points, 

 especially whether or not there exists a relation between the ner- 

 vous supply and the rate with which a part of an organism regenerates. 

 The brittle-stars present certain advantages for such a study, (1) because 

 the operation is not connected with a profuse bleeding, (2) because there 

 are several similar parts which may be operated upon simultaneously, 

 and (3) because the same animal with its five similar arms can be used 



_ Coelomic Cav. 



.... Radial Canal 



Epineural Canal ■■ 



'- Radial Nerve 



Figure A. 



both for the experiment and for the control, the variations incident to 

 the use of different individuals being thus eliminated. 



Unfortunately the want of an abundant material and the great mor- 

 tality among the operated animals prevented me from obtaining a deci- 

 sive answer to all the questions which interested me, and the facts to 

 be presented here form merely the beginning of a more extensive inves- 

 tigation which I hope to pursue at the earliest opportunity. 



Before discussing my experiments and their outcome I will say a word 

 about the anatomy of the nervous system of the brittle-star and about 

 the method of operation. The central nervous system of the Ophiu- 

 roids, unlike that of the star-fish, is a deeply seated organ, and consists 

 of the ring-nerve around the oesophagus, and radial nerves extending 

 out from the ring-nerve into each of the five arms. The ring-nerve and 

 the radial nerves are really double structures, one system being super- 



