The finer Structure of the Nerve Cells of Invertebrates. 21 



In regard to the structure of the bodies of the nerve cells, he 

 finds that they likewise consist of primitive tubes which contain 

 hyaloplasm. He was unable to determine upon the exact mode of 

 distribution of these tubes in the cell, except in the case of some which 

 ran concentrically about the nucleus. 



In addition to the spongioplasm and hyaloplasm, he describes a 

 third substance in the spongioplasm-reticulum, between the primitive 

 tubes, which stains deeply when osmic acid and haematoxylin have 

 been used as fixing and staining reagents. He finds this substance 

 absent from the nerve tubes (axis-cylinder processes), and regards it 

 as partly fatty in character. 



So far as I am able to make out from his description of this 

 substance, it corresponds exactly to what I shall describe in the 

 following pages as chromophilous granules. Nansen entirely disregards 

 the fibrillar theory held by FlemiMing and others. 



The publications of Rohde (33, 34, 35, 36, 37 and 38) known 

 to the writer are six in number. The first five of these papers have 

 for their object, the development of the theory, that the fibrils 

 (Spongioplasma) in the cell body and axis-cylinder processes, do not 

 act as paths along which nervous impulses travel, but serve rather as 

 supporting structures (Stützgerüst) for the semi-fluid hyaloplasm, the 

 true nervous substance, which is contained between them. 



The material made use of by Rohde in these investigations was 

 most extensive, including examples of the Chaetopoda, Hirudinea, 

 Nematoda, Gastropoda and Crustacea. Unfortunately no reference is 

 generally made to the manner in which this material was fixed and 

 stained. 



For the general principles upon which this theory rests, I refer 

 the reader to the following quotation from Rohde's fifth paper (37), 

 p. 387 : "Das Spongioplasma tritt bei den Ganglienzellen in doppelter 

 Form auf, theils als grobfibrilläres, theils als feinfibrilläres ; letzteres 

 bildet stets den Axencylinderfortsatz , breitet sich häufig aber auch, 

 vom Grunde desselben ausgehend, über die ganze Peripherie der 

 Ganglienzelle aus, so dass dann in dieser zwei verschieden aussehende 

 Zonen zur Unterscheidung kommen ; eine innere dunklere grobfibrilläre 

 und eine äussere helle feinfibrilläre (Holzschn. A 2). Die Ganglien- 

 zellen liegen eingebettet in der Neuroglia, welche aus Fibrillen be- 

 steht, die im Aussehen wie in der Stärke mit den groben Fibrillen 

 des Ganglienzell-Spongioplasma übereinstimmen und allenthalben von 

 Kernen durchsetzt werden. An der Peripherie der Ganglienzelle 



