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Tne structure of the nerve-tubes.^) 
The structure of the nerve-tubes: whether it is fibrillous or 
non-fibrillous, has been very much disputed, and to this day jthe 
point must be considered as an open question. Since the valuable 
and important works of Remak, there have, certainly, always been 
plenty of writers to defend the fibrillous structure. Amongst these 
may be named Hannover, 2) Will, Lebert and Robin, Walter, 
Waldeyer, Leydig (only to a certain extent), BOLL, FLEMMING, 
Hermann, Dietl, Hans Schultze, Freud, Vignal etc. Especially 
have Hermann, Hans Schultze and Freud expressed themselves 
very emphatically and distinctly in favour of the fibrillous structure. 
According to their view the contents of the nerve-tubes consist in 
» Frimitivfibrillen « suspended or swimming in an homogeneous semi- 
fluid » Interfibrillårsubstanz « . 
At the same time, however, there have also been others who 
described and asserted a semi-fluid (fest-vveiche) contents, and a 
homogeneous structure of the nerve-tubes in the fresh live state 
(or, also, a granulous structure). Amongst those are Helmholtz,^) 
Hæckel,4) Faivre,^) Owsjannikow,^) Buchholz, Lemoine, Sol- 
1) i prefer the designation nerve-tube lo that of nerve-fibre, because I think 
it more characteristic. 
2) Hannover states, that the nervous tubes of the Mollusca are longitudinally 
striated, whilst those of Astacus have a granular, nebulous substance in a mem 
branous sheath. 
^) Helmholtz described the nervous tubes as «zarthantige Cylinder mit fliissi- 
gen Inhalt». 
^) According to Hæckel the nervous fibres («Primitivrohre) have the form of 
tubes. «Die Wand der Primitivrohre oder die Nervenprimitivscheide ist an den 
feinern Cylindern einfach, an den stårkeren doppelt, immer aber sharf und dunkel 
contourirt, so dass sie sehr deuthlich aus dem umhiillenden matten Bindegewebe 
hervorschimmert.« vDie Inhalt der Nervenprimitivrohre ist wie schon Helmholtz 
erkannte eine dicke Fliissigkeit, welche .... frish .... vollkommen homogen, wasser- 
klar, und leicht glanzend erscheint.« Hæckel has, however, also found Remak's 
«centrale FaserbiindeU and agrees with him, that it might be possible that such a 
one occurs in all nervous tubes. 
^) According to Faivre the contents of the nervous tubes are granulous. »Une 
tube de Sangsue se compose de deux parties: Tenveloppe et le contenu. L'enve- 
loppe est anhiste, sans structure appréciable, sans noyaux, — le contenu des tu- 
bes est formé par une substance finement granuleuse et d'une consistance molle, 
meme å Tétat frais.« Under high powers of magnification this substance is seen to 
consist of very minute granules »agglutinés par une sorte de substance intermediaire 
amorphe«. 
^) Owsjannikow supposes the fibrillous appearance of the tubes to be a 
postmortem product, and he does not believe, that »les tuyaux* described by Stilling 
(in the nervous fibres of vertebrates) really exist in living nervous fibres. 
