518 
pharynx aud the museular coat of the cso- 
phagus, and the heart. In the cesophagus it 
appears to be mingled with the other variety to 
a somewhat uncertain extent. In some speci- 
mens from the human subject I have been un- 
able to detect any striped fibres in the lower 
half of that tube, either in the circular or 
longitudinal layer, but in other examples they 
have been traceable to within an inch of the 
stomach. Among the lower animals consider- 
able differences occur, as has been well pointed 
out by Mr. Gulliver,* who observes that in 
general “the muscular fibre of animal life 
(striped) extended further towards the stomach 
in the outer than in the inner layer of the eso- 
Phageal muscular sheath.” In several animals 
this gentleman found the striped fibres even on 
the stomach (as in the Rabbit, Lepus cuniculus, 
Linn., the Sheep, Ovis aries, Desm., the Sloth 
Bear, Ursus labiatus, Blainv.) while in many 
others he met with them to within a very short 
distance of that cavity. Dr. Todd has also 
shewn them to me on the glandular pouch at 
the cardiac extremity of the stomach in the 
Dormouse. It is stil] unknown in what manner 
the two varieties of fibre are arranged at this 
point of junction, some supposing that they 
are simply intermixed, others that they pass 
into one another by imperceptible gradations. 
The former of these views is that which appears 
Most consonant with my own observations. 
Mr. Skey considers + that the fibres of the heart 
“‘ possess a somewhat compound character of 
texture,” and this opinion seems highly pro- 
bable. They possess, it is true, the transverse 
Stripes indicative of an arrangement of particles 
in parallel series, but there is frequently a want 
of that uniformity and precision in this appear- 
ance which so remarkably characterize voluntary 
muscle. The cross lines are apt to be broken 
and interrupted, and are sometimes difficult to 
discover at all. This condition is well repre- 
sented by Mr. Skey in fig. 5 of his second te 
In some of the smaller and lower animals the 
particles never form transverse stripes. These 
fibres, as explained by him, are smaller than 
the average diameter of the voluntary muscles 
of the same subject by two-thirds, and in most 
parts of the heart they are not aggregated in 
parallel sets, but twine and change their relative 
ition. Striped fibres have been found in the 
iris, in the small muscles of the ear, and in 
those muscular fasciculi that surround the ure- 
thra immediately in front of the prostate. They 
are also found in the sphincters of the anus and 
vagina. 
e unstriped fibre is met with in the ali- 
mentary canal from the middle of the ceso- 
ong to the rectum, and constitutes the double 
ayer investing that tube. It also forms the 
muscular coat of the bladder and that of the 
uterus. The dartos owes its contractility to the 
presence of fibres of this variety, which, in con- 
sequence of the abundant admixture of areolar 
* Proceedings of the Zoological Sociéty of Lon- 
don, No. 81, Sept. 1839. 
+ Phil. Transactions, 1837, p. 381. 
MUSCLE. 
statement. They appear to me to have all t 
tissue, has not hitherto been clearly recognized; 
but it may be detected by the addition of acetic © 
acid, which, by bringing into view the peculiar — 
corpuscles it contains, distinguishes it from both 
the white and yellow fibrous elements of the 
areolar — But even without this pees 
test, to which some may object, it is ible 
to discover this form of becsecii fibre in the 
dartos, by the characteristic ap ces 
have been already attributed to it. Since satis- 
fying myself of the real existence of this fibre — 
in the dartos, | have on many occasions de- — 
tected a very decisive ee action advan- 
cing from one side of the scrotum to the other, 
and continued for a considerable period, yet of 
a kind which it was impossible to refer, with — 
any degree of probability, to the cremaster. 
In one case particularly, occurring in the prac-— 
tice of Mr. Fergusson, where the tunica dartos — 
was much hypertrophied, in connection wit 
an old stricture of the urethra, we observed thi 
peristaltic contraction of a very vigorous 
scription. The fibres which have been ¢ 
scribed as peculiar to the dartos seem to be 
nothing more than a certain modification of the 
areolar tissue in that region. In the 
cavernosa penis of the horse there is a large 
quantity of this kind of fibre, as may be ascer- 
tained by microscopic examination, although 
Professor Miiller* seems indisposed to consid 
it really muscular. He states that “ viewed 
the microscope these fibres do not n 
resemblance to muscular fibres,” but my ow 
examinations of them have not confirmed 
OTDO 
characteristics of this variety, and by t 
acid are seen to contain a great number of : 
puscles. Moreover they appear to consist che 
mically of fibrine. Professor Miiller has fail 
in exciting contraction in them in the 
horse, but this is not a conclusive fact as 
their nature, for it may be and probably a he 
case that they do not act unless strete 
erection of the organ. In the quiescent co 
tion of the part they may be considered to 
in a contracted state, like the muscular co 
an empty intestine, and so would natu 
appear to be unaffected by the stimul 
galvanism. The erection of the penis § 
with great probability to be attributab 
pressure exercised on the superficial ve 
the organ by a continuation of a structure 
logous to the dartos, and certainly con! 
the unstriped muscle, which is continues 
the base of the penis under the skin. 
erection of the nipple also occurs, on an 
chanical irritation, with a motion so very 
resembling the peristaltic action of imu 
fibres, that I have little doubt such wou 
found, constituting a layer, under the skin 
region. And it may be matter of ing 
far the general contractility of the skin 
pendent on a diffusion of this tissue, — 
quantities, throughout its areolar s : 
excretory ducts of all the larger glands a 
to possess a covering of fibre belonging 
d ive 
hy 
oy 
ens 
* Physiology, by Baly, second edition, p.' 
