MY PREDECESSORS. 399 



gestion ; the mere fact of a sympathetic ganglion being 

 connected with a nerve which, although fibrous, has its 

 interspace of granules, is enough to destroy the hypo- 

 thesis ; not to mention the fact of so many animals 

 being without fibres at all. * 



From what has been already said, the conclusion is 

 inevitable that the conduction of nerve force does not 

 take place hy means of fibres only. The fibres may 

 be special organs of conduction, and as special organs, 

 a corresponding specialty of function must be assigned 

 to them ; and into this we must now inquii^e. 



Let us assume that the homogeneous nerve trans- 

 mits the impression in a mass, just as the sounding- 

 board of a piano, if struck, will yield a certain reson- 

 ance ; but the fibrous nerve will transmit the impression 

 along each separate fibre, like the sounding-board when 

 struck by keys ; the amount of nervous impression and 

 the amount of sound in each case may be equal, but 

 the varieties and combinations possible to the latter 

 are impossible to the former. Or, to vary the illustra- 

 tion, let us assume two men to be equally susceptible 

 to the general effect of colour, but one of them, an 

 artist, to have more susceptibility to the minute differ- 



* Meissner's observations furnish a very noticeable fact, namely, that 

 while in Merviis Albicans the trunks are homogeneous, in another 

 species, Mermis nigrescens, they are fibrous ! In the face of such evi- 

 dence no single exception to the facts I have stated would surprise me 

 — for instance, that fibres could be found in a Doris, a Pleiirohranchus, 

 an Aplysia, or a Solen — such exceptions would in nowise invalidate my 

 conclusions, for which, indeed, one single case of non-fibrillated nerve 

 would be ample evidence. [I have since found fibres in the nerves of a 

 Doris.] 



