374 
MR. SKEY ON MUSCULAR FIBRE. 
which subsists between the circular striae and the longitudinal filaments beneath 
them, the latter being- connected tog-ether in bands around the tube of the fibre, each 
band containing- about eight or ten filaments, and the appearance of an angular 
arrangement of the striae is produced by the partial separation of these portions of 
the fibre from each other. The uniformity of this separation, of which each fibre is 
susceptible, appears to warrant its subdivision into these bands, which I propose to 
name “ Fibrillce these again being subdivided into “ filaments .” 
If a fibre be partly unravelled, this irregular and interrupted appearance of the 
striae will be rendered still more apparent (fig. 3.). 
Of the anatomists whose names I have mentioned, Proschaska has given the most 
minute description of the transverse striae, and yet judging from the plates attached 
to his work, “ De Carne Musculari,” he must either have seen them with imperfect 
microscopic powers, or the delineations by the artist have done injustice to his de- 
scriptions. 
It is, perhaps, somewhat remarkable that the striae are not seen with equal di- 
stinctness, in all the muscular fibre of animal life. When distinct, they present them- 
selves in the form of well-defined rings, the extremities of which may be distinctly 
traced, encircling the fibre equidistant from each other, uniform in diameter, and ap- 
parently elevated from its surface into ridges, leaving depressions between them ; and 
when a fibre is sufficiently bent to render its convex edge somewhat tense, they very 
apparently stand out from the plane of the fibres, forming circular ridges around it, 
and presenting the appearance of a fine serrated edge. When very large they occa- 
sionally form distinct bifurcations or loops, but pursue their course with the utmost 
regularity. 
Although the striae exhibit the character above described, of elevated rings cross- 
ing the fibre, they present in different examples some variety in appearance. For 
the most part the dark lines are narrower than the light which alternate with them. 
Sometimes the dark appear elevated, the light or colourless striae forming the de- 
pressions. At other times this appearance is reversed, and the elevated striae appear 
to be formed by the intervals between the darker lines. 
It is not easy to determine the question by tracing these to the margins of the 
fibre, because the entire fibre is not in focus at the same time, and the slightest move- 
ment of the field of the microscope distracts the eye from the point of observation. 
After adopting various modes of inquiry which led to no satisfactory conclusion, 
accident ultimately convinced me that the opinion I at first entertained was erroneous. 
I obtained a fibre, torn in the longitudinal direction, in which it was evident that the 
lines of separation corresponded uniformly with the dark striae, the light, although 
distorted from their straight direction, remaining- unbroken, and pursuing a distinctly 
continuous course across the fibre (See Plate XIX. fig. 5.). 
I infer, therefore, that the light are the elevated striae, and the dark intervening 
lines, the depressions. After five years immersion in spirit I find them as distinct 
