96 
DR. MARTIN BARRY ON FIBRE. 
102 a, (3, y), having the same structure as those constantly referred to in the pre- 
sent memoir. These filaments, forming the white substance of the nervous fibre, are 
often seen to be curiously interlaced (fig. 102 y), as though each filament had a spi- 
ral form. In other instances their direction is more longitudinal (fig. 112 a). 
29. Professor Muller justly says, “The great size of the so-named primitive fibres 
of the nerves, as compared w ith the minute elementary parts of muscles, the cellular 
and other tissues, excites a doubt as to whether the fibre contained in the nervous 
cylinder is really its most minute element-!-.” He states that “in fibres of the thick- 
ness of the ordinary primitive fibres, which Schwann examined in the mesentery of 
the Frog, he saw other much finer filaments which issued from the larger fibre;};.” 
To the filaments seen by Schwann, I shall refer in a future page. Muller adds, that 
“Treviranus observed in several nervous cylinders streaks running longitudinally, 
and he even saw distinctly more minute elementary filaments in the so-called primi- 
tive cylinders §.” 
30. The filaments noticed by Treviranus, I think may have been the flat filaments 
in question. But these flat filaments, as we have seen, have themselves a compound 
structure. 
31. It is very common to find the nerve-cylinder (“primitive fibre”) drawrn out to 
a point from manipulation, like the fasciculus of muscle. See remarks on the alter- 
ation of the spirals in the muscular fasciculus, and on the office performed by the in- 
vesting membrane, in this change (par. 54). 
32. The filaments in fasciculi from the optic (fig. 107), olfactory (fig. 108), and audi- 
tory nerves, have appeared less tense than those in the common spinal nerves ; and 
there has been a less decided appearance of membrane at the surface in the former. 
33. In examining the substance of these soft nerves, as well as that of the brain 
and spinal chord, I have employed for the most part such as had been preserved in 
spirit : and, besides using extremely minute portions, I have very often found it need- 
ful to avoid adding any covering whatever ; the weight of thin mica itself being suf- 
ficient to rupture or to flatten it, and thus entirely prevent the structure from being 
seen. I have already stated it to have been* my general practice in these examina- 
tions, to add corrosive sublimate dissolved in dilute spirit (par. 7)* 
34. In the substance of the brain and spinal chord, I have usually met with a very 
large number of discs (fig. 17 «, (3), wdiich from their colour, size, and general appear- 
ance (corresponding in these respects with many of the corpuscles within the blood- 
vessels of the pia mater), seemed to be young corpuscles of the blood. Along with 
these were rings (y) and coils of filaments (c$, s, e), into which the discs appeared to 
pass. I have noticed similar rings in the auditory and optic nerves ; and coils, as 
well as rings, in the retina (fig. 18), these coils being of the colour of the blood-cor- 
puscle. Sometimes the coils (fig. 21) are very thick, and comparable to coils of rope. 
t Elements of Physiology, translated by Dr. Baly, Part III. p. 597. 
J Ibid. pp. 597, 598. § Ibid. p. 598. 
