MR. SKEY ON MUSCULAR FIBRE. 
373 
The muscular fibres of animal life, possess a very varying diameter, but their average 
size, and that which largely predominates, may be stated at about ^m^th of an inch ; 
but they may be found of all magnitudes, from the ^fg-th to the T -^th of an inch. 
If the object be separated from the mass with a pair of scissars, the extremities of 
many of the fibres will be compressed and closed, but they retain their natural dia- 
meters up to the extremity, if separated with a lancet or knife; this therefore is pre- 
ferable. 
When the object is clearly in focus circular striae are exposed, crossing the fibre 
along its whole length (Plate XVII. fig. 1. a.). These were known to and delineated 
by Leuwenhoek, Muys, Proschaska, Fontana, and others. By the former eminent 
physiologist they were delineated but coarsely, and as existing at irregular intervals 
from each other ; and judging from the plate by Proschaska, they were but imper- 
fectly known to him ; yet he has devoted a large portion of one entire chapter to their 
description. Fontana’s work, however, “ Sur les Poisons,” contains a beautiful re- 
presentation of the transverse striae, which both for correctness and for effect cannot 
well be surpassed. They are seen more or less distinctly in the fibre of animal life in 
all the examples I have examined, but most distinctly in that of the Ox, the Hog, the 
Ichneumon Fly, and the Blatta Americana (Cockroach). In the two latter they form 
prominent and elevated bands, resembling in their magnified form the rings of the 
human trachea (fig. 2. a b.). Straus states that the muscular fibre of the Me- 
lolontha vulgaris (Cockchafer) is similarly serrated. 
The transverse striae are placed closely together, but varying much in thickness 
and in number, a portion of the length of the fibre equal to its diameter containing 
from 16 to 25. They sometimes appear uninterrupted in their course across the 
fibre, and occasionally exhibit the appearance of shorter interrupted lines, which, sur- 
rounding it, present the aspect of a cylinder of a polygonal form (fig. 1. b.). In 
the plate of Fontana the striae are represented of each variety in the same object. 
I believe this appearance, which is both frequent and regular, to arise from violence 
to the fibre, and to be neither natural to its structure nor dependent on optical decep- 
tion. This arrangement has given rise to the opinion by Proschaska, that the muscu- 
lar fibres were polyhedral cylinders. It must be observed, however, that this is not an 
uniform appearance, but that the transverse strise are more generally arranged in 
continuous and uninterrupted circular lines around each ultimate fibre. I have re- 
marked that if great care be taken in the preparation of the object while under the 
dissecting microscope, this broken arrangement is rarely visible ; and considering the 
improbability of the co-existence in the living fibre of both the series described, as in- 
consistent with the simplicity of nature, and the impossibility of converting by any 
manipulation the interrupted into the continuous and ^interrupted strise, I cannot 
doubt but that this apparently angular arrangement is due to so many artificial de- 
pressions of a mutilated j£6re. 
The regularity of the appearance I conceive to be produced by the connection 
3 c 2 
