SECTION OF COVERED-EYED MEDUSA. 79 



appeared ; for just as in a piece of muslin the con- 

 stituent threads, although frequently meeting one 

 another, never actually coalesce, so in the nervous 

 network of Aurelia, the constituent fibres, although 

 frequently in contact, never actually unite. 



Now, if it is a remarkable fact that in a fully 

 differentiated nervous network the constituent 

 fibres are not improbably capable of vicarious action 

 to almost any extent, much more remarkable does 

 this fact become when we find that no two of these 

 constituent nerve-fibi-es are histologically continuous 

 with one another. Indeed, it seems to me we have 

 here a fact as startling as it is novel. There can 

 scarcely be any doubt that some influence is com- 

 municated from a stimulated fibre a to the adjacent 

 fibre h at the point where these fibres come into close 

 apposition. But what the nature of the process 

 may be whereb}^ a disturbance in the excitable 

 protoplasm of a sets up a sympathetic disturbance 

 in the anatomically separate protoplasm of 6, 

 supposing it to be really such — this is a question 

 concerning which it would as yet be premature 

 to speculate. But I think it may be well for 

 physiologists to keep awake to the fact that a 

 process of this kind probably takes place in the 

 case of these nerve-fibres. For it thus becomes a 

 possibility which ought not to be overlooked, that 

 in the fibres of the spinal cord, and in ganglia 

 generally, where hi.stologists have hitherto been un- 

 able to trace any anatomical or structural continuity 

 between cells and fibres, which must nevertheless 

 be supposed to possess physiological or functional 



