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the nerve-tubes gave always the impression that they could have 
been produced by the sheaths of those slender tubes being split 
longitudinally and thus forming fibrillæ. The viscous substance is 
certainly very often seen adhering to these fibrillæ, but if we look 
carefully we will see that it always is in the form of small pearls 
adhering to the sides of them; I have never observed pearls quite 
surrounding, or embracing, a filament, which certainly ought to occur 
occasionally if the filaments were round fibrillæ swimming in an 
interfibrillar substance in the nerve-tubes. 
I have not been able to obtain any further information regard- 
ing the structure of the tube-contents from fresh preparations. 
If we examine macerated preparations we will not become 
much wiser, and neither do they suffice to solve the riddle as to 
the real nature of the fibrillar structure. 
The quickest and easiest method of maceration is that indicated 
by Bela Haller (cmfr. p. 73 — 74). In that way an isolation of the 
tubes is possible even after a lapse of one or two hours; the tubes 
exhibit a distinct sheath, with sheath-nuclei, as well as a distinct longi- 
tudinal striation of their contents (fig. 15); a staining is not necessary. 
In successful preparations you may find nerve-tubes with extremities 
more fibrillar and brush-like than any of those obtained in fresh 
preparations. With a good will and skilful hand you can, by 
teasing with fine needles, even improve this fibrillar appearancc^ 
nay, you can split not only the tube contents but also the sheaths 
longitudinally into filaments or »fibrillæ«. This shows, however, 
that these fibrillæ can be artificially produced, because most writers 
agree in declaring the sheaths to be homogeneous membranes of 
connective substance (muroglia). If we now examine the fibrillæ 
under high magnifying powers we will find them all to have the 
same, somewhat irregular appearance both, those from the tube- 
contents as well as also those springing from the tube-sheaths. If 
we try other maceration fluids (e. g. weak sol. of alcohol, amm, 
bichr. 0.03%, potass.-bichr. o.i — 0.03 Langdoiss fluid etc.) we 
obtain very similar results. By all these methods we arrive at the 
^) In Pl, II fig. 13 an appearance of the nerve-tubes is illustrated which I 
have often noticed in the fresh state, and which easily could give rise to serious 
mistakes. «, a are the hyaline-looking contents of the nerve-tubes (belonging to a 
peripheral nerve); 6, h are the sheaths from which septa (c, C, c') aparently issue 
and penetrate into the contents of the tubes. These apparent septa are, however, 
an optic illusion only artificially produced by a slight hending of the nerve in 
which the nerve-tubes are situated. 
