398 JOHN BEARD, 



these figures were taken; their number could have been much in- 

 creased , and other examples from other forms may possibly find 

 a place among the figures of part II of the work. All the cells 

 of the figures cited are "nerve - cells" , or, in other words, all 

 retain traces of ganglionic origin. The cells are bi-polar, and their 

 processes are axis-cylinders. An examination of the figures reveals a 

 gradual passage from undoubted ganglion-cells, like some of those of 

 Fig. 79, through cells which have still marked ganglionic features, to 

 such as have hardly anything in common with bipolar ganglion-cells, 

 except that , like them , they have given origin to nerve-processes 

 leading in two directions from the parent-cell. For the present these 

 few remarks may suffice, and the point may profitably be reverted to 

 at some future period, when the origin of nerve and of nervous 

 structures may be under consideration. Any history of these latter 

 must take account of the variations among ganglion-cells; for every- 

 thing points to the primary existence of these, and — it is a truism 

 — without ganglion-cells there can be no nerve. 



Preliminary remarks on permanent giant ganglion -cells 



in other forms. 



The following remarks to the end of the paper are intended to 

 be of a preliminary character. 



As intimated at the commencement of the present communication 

 it is proposed that a second contribution, dealing with the transient 

 nervous apparatus of some other Ichthyopsida , should be published 

 with as little delay as possible. It may therefore be convenient to 

 postpone any detailed consideration of the theoretical aspects of the 

 work until then. 



For, although in some other Ichthyopsida the transient system 

 can be shown to' possess features very similar to those here ascribed 

 to it in Raja, there are great differences in the degree of its de- 

 velopment, and, as stated in a preliminary paper * ), it appears to be 

 entirely absent in certain viviparous fishes, the gulf between the two 

 extremes being partly bridged over by Mustelus vulgaris. Until all 

 the facts obtainable are brought to bear on the problem it would be 

 premature to discuss, except a preliminary fashion, the general mor- 

 phological nature of the apparatus from what is known of it in one torm. 



From an early stage of the investigations it was foreseen that 



1) No. 2. 



