MUSCLE. 
tudinal” (doubly-spiral, flat,) “ filaments are con- 
tained and have their origin.” 
This description, so entirely opposed to the 
more simple view above given (and which was 
already in type when the paper “ On Fibre” 
was read) demands a brief notice. The paper 
of which it forms part, might perhaps have 
been more explicitly entitled, ‘‘ On the double 
spiral structure of the organic world;” for, 
in it, the doubly-spiral flat filament, giving the 
appearance of transverse strie to voluntary 
muscle, is discovered to exist in the interior 
of the blood-corpuscles of all animals, and 
* apparently in every tissue in the body. The 
author enumerates a great variety of organs in 
which he has observed the same kind of fila- 
ments.” “ And if the author’s view of iden- 
tity in structure between the larger and the 
smaller filaments be correct, it follows that 
spirals are much more general in plants them- 
selves than has been hitherto supposed ; spirals 
would thus appear, in fact, to be as universal 
as a fibrous structure.” “ Valentin had pre- 
viously stated, that in plants all secondary de- 
posits take place in spiral lines. In the in- 
ternal structure of animals, spirals have here- 
tofore seemed to be wanting, or very nearly so. 
Should the facts recorded in this memoir, how- 
ever, be established by the researches of other 
investigators, the author thinks the question in 
future may perhaps be, where is the ‘ secon- 
dary deposit’ in animal structure, which is not 
connected with the spiral form? The spiral in 
animals, as he conceives he has shown, is in 
_ strictness not a secondary formation, but the 
_ Most primary of all; and the question now is, 
_ whether it is not precisely so in plants.” 
As these speculations profess to be grounded 
solely on observations of particular structures, 
of which muscle is one, I shall make no apo- 
logy for applying my few remarks solely to the 
_ account of this structure, which is all that can 
_ properly be considered here. A renewed ex- 
amination of this tissue has confirmed, fully 
and decisively to my own mind, the account 
I gave of it in 1840, and which was the result 
of two years’ study. 1.1 find that when the 
natural and ready cleavage happens to be into 
fibrillee (and I do not pretend to explain why 
_ this cleavage should be at one time into fibrillz 
_and at another time into discs, I only know 
the fact,) these solitary and isolated fibrille do 
not present any such central longitudinal 
groove, as Dr. Barry describes, to indicate 
their double nature: that the cross lines are usu- 
ally transverse, and not oblique, by which I 
mean that the spaces they bound have a rectan- 
gular outline, so sharp and definite, that the 
tnind rests entirely satisfied that there cannot 
_ be two opinions concerning them, between 
any who have examined the object in one of 
owell’s best microscopes, and with the use of 
admirable definer and clarifier of the 
the achromatic condenser. That right 
a can be produced by a spiral, whether 
_ double or single, however distorted by accident 
_ or violence,’ it is impossible to conceive. That 
these transverse lines may sometimes become 
‘oblique by irregular traction, such as is almost 
511 
necessarily applied in preparing the object, is 
most easy to understand, if we bear in mind, 
that the substance in the different spaces which 
they cireumscribe is one united mass. 2. The 
transverse cleavage of the elementary fibre, 
which I first showed to be occasionally so com- 
plete as to separate it into discs, cannot be 
reconciled with Dr. Barry’s statement. For 
the surfaces of such discs present, as in fig. 
288, a fine granular aspect, and no ends of 
doubly spiral threads. And the definite and 
beautiful appearance presented by a transverse 
section of the fibre in all animals, but espe- 
cially in Birds (fig. 290), is totally at variance 
with his views: for the particles there dis- 
played are highly refracting, round, and not 
aggregated in pairs. The condition repre- 
sented in fig. 289 is not less opposed to them. 
Other proofs might be adduced, but they 
would lead to greater detail than is compatible 
with the form of the present publication; and 
perhaps they will be allowed to be unneces- 
sary. 
6. Of the corpuscles of the elementary fibre. 
The elementary fibres always contain, among 
their primitive particles, a number of corpuscles, 
which either are, or are analogous to, the nuclei 
of the cells of development, of which this 
and other structures have originally consisted. 
These corpuscles are visible in the early stages 
of growth (fig. 291), but disappear towards 
the close of fcetal life, as the lines resulting 
from the deposit of the contractile particles 
Fig. 291. 
a 
= pepe et 
iss 
Elementary fibres from the pectoral muscle of a fetal 
calf about two ths after conception, shewing the 
corpuscles at a, a, a. Magnified 300 diam. 
Fig. 292. 
Fig. 293. 
Elementary fibre from the leg of the large Meat-fly 
( Musca vomitoria ), 
a, a, line of termination of the fibre, along which 
the tendon (6) is attached to it. 
¢, central series of corpuscles. 
Along the margin the sarcolemma is elevated by 
water, (which has been absorbed, ) and is thereby 
shown to be adherent to the margin of the dises, 
