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Boll (1869) says: »Die Ganglienzellen der Mollusken bestehen 
ebenso wie bei den Wirbelthieren aus zahlreichen in den verschie- 
densten Richtungen verlåufenden åusserst feinen Fibrillen und aus 
korniger interfibrillærer Substanz. Eine besondere Membran fehlt« 
(1. c. 1869 p. 19). »Die Nervenfasern, die Fortsatze der Ganglien- 
zelle gehen stets aus der Substanz derselben hervor in der Art, dass 
die Fibrillen an den Abgangsstellen der Fortsatze eine bestimmte 
parallele Richtung annehmen und sich zu mehr oder minder feinen 
Strangen zusammenlegend von dem Zellenkorper abtreten.« 
DiETL (1877) describes a concentric striation of the cell-proto- 
plasm, in preparations treated with osmic acid. This striation he sup- 
poses, however, also to exist in the live-state. The striation circulates 
round the nucleus and can always be traced directly into the pro- 
cesses of the ganglion cells. In the brain of Tethys fimhria he des- 
cribes ganglion cells containing a peculiar »protoplasmatisches Balken- 
netz, das die Verbindung des Zellkorpers und des Fortsatzes ver- 
mittelt« (1. c. 1878 p. 524). 
Cadiat (1878) does not, exactly, tell whether he supposes the 
ganglion cells of the Cmstaceans to have a fibrillar structure in the 
live-state ; their protoplasm is, however, in his opinion, quite identical 
with the contents of the nerve-tubes, and in the latter he has 
occasionally observed fibrillæ. He further states that, on application 
of nitric acid he has seen a striation in the nerve-tubes and »la meme 
striation se voit sur les cellules et leurs prolongements immédiats.« 
The author who has most distinctly declared himself for a 
fibrillar structure, and who, in my opinion, has made the closest and 
most convincing investigations on this subject is Hans Schultze 
(1879). He has defined the point in debate, and has concentrated 
his investigations upon it, but neither has he been quite successful. 
According to the result of his investigations, the protoplasm 
in the ganglion cells, as well as in their processes and the nerve- 
tubes, consists of >^Primitivfibrillen« and »Interfibrillår-Substanz«; 
everyone of the fibrillæ is surrounded by interfibrillar substance, 
they must, consequently, in a manner, swim in it. If that, 
however, is correct, why then has Schultze, as well as everyone 
else, succeeded so badly in isolating these freely swimming fibrillæ? 
why can we only obtain a sort of isolation of them in the ex- 
tremities of teased processes or tubes, and not in the cell-protoplasm 
itself? 
To this question Schultze has given no reply, nor has any- 
body else, so far as I know. 
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