274 PROFESSOR MARSHALL. 



favour of his view, "which, on the other hand, is opposed merely " by a 

 theoretical homology, a preconceived notion of what Crinoids ought to 

 be." He concludes with some important observations on the morpho- 

 logical aspects of the question, which will be noticed in a later section 

 of this paper. 



The present position of the question may be briefly described thus. 

 The Carpenters and Perrier, on the one hand, maintain that the central 

 capsule and axial cords, with their branches, constitute the essential 

 and principal part of the nervous system, both motor and sensory, 

 while the subepithelial bands, if nervous at all, are of very subordinate 

 functional importance. On the other hand, Ludwig and the German 

 morphologists generally maintain that the subepithelial bands consti- 

 tute the sole nervous system. The former school cite in support of 

 their views a large mass of anatomical and histological observations 

 and certain direct experiments ; while the latter school rely entirely 

 on theoretical morphological objections to the views of their opponents. 



III. Experimental Investigation op the Nervous System of 

 Antedon rosaceus. 



This section of the paper, containing the account of my own 

 investigations made at Naples last April, I propose to subdivide under 

 the following heads : — A. The movements of uninjured specimens. 

 B. The effects of removal of the visceral mass. C. The power of 

 regeneration. D. The functions of the central capsule. E. The 

 functions of the axial cords. F. The functions of the subepithelial 

 bands. 



A. The Movements of Uninsured Specimens. 



The normal position of Antedon rosaceus, the species on which all 

 my experiments were made, is a fixed one, the animal being attached 

 by the dorsal cirri to some foreign body, and the arms spread out 

 horizontally with their tips slightly flexed. The oral pinnules are 

 bent over the disc, crossing one another above it ; the other pinnules 

 are spread out nearly at right angles to the arms. 



In an aquarium containing a large number of specimens the great 

 majority will be found attached either to the bottom or sides of the 

 tank, i.e. with the oral surface directed either upwards or more or less 

 obliquely ; some specimens, however, are almost certain to be found, 

 if there be foreign bodies in suitable positions for attachment, inverted, 

 with the oral surface downwards. 



