376 
MR. SKEY ON MUSCULAR FIBRE. 
But each fibre is a compound structure, and is surrounded externally by the cir- 
cular striae I have above described. A fibre may be reduced to its apparent elements 
by a successful manipulation, which will exhibit its ultimate structure, composed of 
a series of longitudinal lines or filaments, placed parallel and in close apposition to 
each other, around the axis of the tube of the fibre. These are the ultimate known 
filaments of muscular texture, and of which each fibre of the diameter of -^n^th of an 
inch contains from 90 to 100. 
They may occasionally be separated from each other, forming a sort of tasselJed or 
brush-like extremity of the fibre they compose. Their diameter I conceive to be 
about the - ^yyg th part of an inch (Plate XVII. fig. 3. c c.). 
I have examined these filaments with great care, and with a magnifying power, 
nearly 200 times greater than that employed by Sir E. Home and Mr. Bauer, and I 
am compelled to differ from these gentlemen in favour of the opinion, first promul- 
gated by Messrs. Hodgkin and Lister, that they are ?minterrupted threads or cylin- 
ders, and neither composed of the globules of the blood, nor possessing even a glo- 
bular arrangement. 
I have carefully compared a filament magnified by 600 diameters with the plate by 
Sir E. Home in the Transactions of the Society, and I find that neither the human 
filament nor that of any animal in which I have observed it, is nearly so large nor 
so distinct as that represented in the above plate. Yet Mr. Bauer’s magnifying 
power was 200 diameters less than that of Mr. Goadby’s which I employed. Be- 
clard, M. Edwards, Prevost, Butrochet, and Dr. Grant, have adopted this view 
first promulgated by Sir E. Home. Fontana, who has delineated the fibre of muscle 
so accurately, and who applied a single lens of -gUth of an inch focus, asserts them to 
be cylinders, hollow or solid, and only occasionally presenting a globular appear- 
ance. 
It should be particularly observed that the circular striae which surround each 
fibre are closely adherent to the most projecting surface of each longitudinal fila- 
ment. These latter, when detached into separate shreds, occasionally exhibit on their 
surface, the marks or indentations corresponding to the distance between the circular 
strife on the whole fibre (fig. 3. d d.), and I think the filament will present the more 
or less distinct appearance of a globular structure in proportion to the distinctness 
of the circular striae. 
In the Haddock and the Cod, the fibres of which are very large, and in which the 
circular striae are of extreme beauty and delicacy, the ultimate filaments present no 
appearance of a globular arrangement, but are distinctly continuous and uniform 
throughout their whole length. 
Probably the best test to which they can be submitted is that of placing the glo- 
bules of the blood and some muscular filaments, under the field of the microscope at 
the same time. When subjected to this mode of inquiry, the filaments will be ob- 
served to be excessively minute, and the globules of the blood may be seen floating 
between and behind the different fibres, in the apparent breadth of about twelve to 
