396 JOHN BEARD, 



only explicable on the "process" theory, but in a vast material only 

 a few such. 



To make a long story short, the inquiry seems warranted, whether 

 a compromise between the two camps may not be ultimately necessary, 

 whether in point of fact both modes may not occur, and whether the 

 "cell-chain" mode may not be predominant in lower forms, while, in 

 the course of evolution, it may not have been substituted by the "pro- 

 cess" method in higher forms? 



Of course it is not forgotten that the nerves of the transient 

 system are stated to be largely processes of ganglion- cells, and that 

 at the same time the apparatus is considered to be of a lowly type. 

 The nerves are of small size, and the longest transient fibre observed 

 only equals some thirty times the diameter of the ganglion-cell from 

 which it springs, or, even if only the first half of its course had been 

 detected, a length of some sixty times the diameter of the parent-cell 

 is a very different thing from one of twenty thousand times such 

 diameter, and the latter would often follow as the ratio of ganglion- 

 cell and nerve according to the view of His. 



Further consideration of this question and of that of the evo- 

 lution of nerve may perhaps find a place in Part II of the work, and, 

 in the meantime, the brief statement may be permitted that my 

 own present view of the evolution of nerve coincides in some respects 

 with that outlined by the brothers Hertwig in their "Medusen" 

 memoir. There are indications in this direction in more places than 

 one in the present paper. 



Finally, it may be insisted that the question is still an open one, 

 and the aim of the above discussion has been to point this out, as 

 also the signs tending towards an ultimate compromise. 



The degradation of ganglion-cells. 



Under this title it is intended to describe a sort of reduction or 

 degeneration of ganglion-cells to the condition of mere nuclei embedded 

 in a nerve-fibre. I am unaware that this factor has as yet received 

 due recognition ; certainly there would appear to exist no appropriate 

 terra by which to describe it. 



By degradation of ganglion-cells is meant the losing 

 of specif ic gangl ionic characters and functions, when 

 a cell, whose phylogenetic history is ganglionic, sinks 

 to the position of a mere nucleus in the conducting 

 fibre to which it has given origin. 



