Section I.
DISPOSITION AND FORM OP THE MUSCULAH FIBRKS.
Thk muscles consist of buudles of fibres, which are tbeiDiseh-es composed of more delicate filaments, h«Id together by a loose cellular tissue Tiiis etructure it) visible to the naked eye ; but a powerful lens is re([uired to ascertain the more minute texture of Uie part. If one of the most delicate filaments be placed on a piece
a K 2
420
DIVISION OF MUSCLE INTO nift
of glass, lineft mity be seen l)y the microscope, which run parttlle! to the direction of ihc fibn-, indifnting a further division than lutd prcnously b«en detected} at length H fine thread is obaiervcd, which, Ijein^ tncs- pable of division, has hecn called by writers the uUontrir mitsculnr fibre. Vnrious terms have been employed in order to designate these snccessive divisions. Muys, k Dutch anatomist, who paid great attention to thiB-ntfa* ject, divided the muscular KubRtance into fibres, fibriUie, Olid threads ; and he subdivided these again into seven] gradations, bo that he made no less titan nine diviRiotu, succe^isivcly dimiaiidiing ; the fibrils, of which the XaA series is compoH^d, being some hundred times smaUo* than the tinest hair. Other obKen'ers bare reacted tfafa analysis as altogether imaginary ; but in doing this tbcy have committed a much more serious error, by admittinf an indefinite divisibility. It is almost needless to state, that in the muscles, as in (dl other materiid 8u)>staDCCS, we must arrive by microscopic inspection, provided our instruments be sufficiently powerful, at a degree of di^H- sion which is ultimate and determined.
It will answer every useful purpose if the muscle be divided into fascicuii, fibres, and filamenit; by the fint word in understood tliose imndles which ore seen by the naked eye to consist of distinct fibres ; the second term shoidd be applied to the smallest division that un be perceived without the assistance of a magnityia; power ; and lastly, the term filament, correspondiog with the vitimate fibre of authors, indicates the butt di- vision of which the muscular structure is susceptible. >
The faadctdi, called also lacerti, arc much mora rip- parent, from their great size, in some muscles tlian in others ; thus they are vay krge in the gluu-us miiximui.
FASCICULI, PIBRB9, AND FILAMENTS.
liw dfUoid, the cariicsc columnae of the heart, and in tJie longitudinal bandii uf the colon. la other instunces they are indistinct, and then; are evva muscles, wliich in their entire hulk, scnrcely equid the volume of a part of one of the preceding bundles.
iti The fitn-fs differ from the fasciculi by being almost always of tlie same size ; their form, which is prismatic pentagonal, or hexi^nal, but never cylindrical, is nearly the name in all parts ; they can be shewn, by a lon- gitudinal dissection, but they arc more distinctly seen by cutting the muscle transversely, especially after it has been hoiti.<d, or maccrntod in alcohol. The 5bres appear to extend in a continuous manner, from one ex- tremity of the muscle to the other, and this, according to Prochaska, Bichnt, and others, is actually the case, even in such long muscles as the sarlorius. But a dif- ferent opinion was entertained by Albinus and Haller, who thought that each fibre was jointed or made up of a number of pieces. Inspection seems to confirm the former statement, so that the length of tlie fibre being determined by that of the muscle, must be extremely various.
The ultimate filament Ls so very minute, that a high magnifying power is required to render it apparent ; .this great tenuity and the uncertainty of microsco- pical observations, are the causes of the contradictory accounts which have been published on tliis Hubject. From the time of Lecuwcnhoek, to the present day, anatomists have been occupied in endeavouring to de> tcrmine the exact composition, size, and other quajities, of the ultimate fibre, but with such tittle success, that scarcely any two writers agree in their coocludionit, Aa there is m much discrepancy in the opinions of the
433
HICRDSCOPICAL ACCOUNT
bighest authorities od thU subject, I shnll only aUude, in a brief manner, to tht latest resuarches which have been made in this country and on the continent.
Sir A. Carlisle, who has published some instructive ob- si'n'atioiis on the anatomical structure of Uie muscular fibre, states that it in undoubiL-dly a solid cylinder, the covering of whicli is reticulatod membrane, and the con* tained |>art a pulpy «ubiitance irrqiuhirly granuiaied, sad of Uttle cohesive power witen dead, ll is dibtinctly afiinned, that the intrinsic matter of muscle con&uned within the ultimate cylinder, has no red particles.
Subsequently to thiis description a very different MS^H count has been given by Mr. Bauer and Sir K. UoitwH At tlie request of tltc latter, Mr. Bauer examined, with the Hid of high magnifiers, the ultimate muscular fibre, and he found that it was composed of a series of glo* bules of the same size with tliose of the blood, when deprived of tlieir colouring matter; it Js even stated that when the fibres are macerated for a sufficient lime, having been previously boiled or roasted, they may be readily broken down into u ma&s of globule!;. Tbt diameter of the particles of the blood, when deprived of their colour, and conHei)ucntiy of the muscular fiW raent, Ls.j^-^ part of an inch.
The iclea of a globular structure is not of modern origin. Leeuwenhoek, in his first publication,* affirmed that tlie fibres were composed of globules ; it is true, h« afterwards changed his opinion, and contended against Ilooke, that the globular appearance was deceptive, be- ing produced by tlie unequal reflection of light from numerous transverse foULs which he had observed on the
• Pbil. i'l
lfi74.
Of ULTIMATE riBRE. 423
fibres. T)i« existence of gtobiilea, or of corpuscles' having nearly Ihe same form, was admitted by many celcl>r«tP(l anatomist** after Leeuwenlioek ; thus Ihe mus- cular fibre was often compared to a scries of pearU, to grains of coral, rows of beads, &c.
The researches of ttevcral modern continental physio- Inglstn, amoii|!f;t whom may be omirnoratod Uumns. M. Edwards, and Oulrochet,* correspond in their essfntiwl ■('points with those of Mr. Bauer.
Notwithstanding the high authorities who contend for the globiUar slnicture, and the very general awent this doctrine has received, 7 an* induced, from the in- vestigetions of Dr. Hodgkin and Mr. Lister, and firom my own observations, (o doubt its correctness, 1 have repeatedly examined, with the aHsiKtaiicc of my friend, Mr. T. Cooper, Ih* muscular fibre. Wc have uniformly found, by using a magnifying power of 300, that an
- Thii ili>tinf;ui>lie>l snalniniit iind naluraliM lint published some iulerot- ia(( tcmsfki on Ihe ibucltim of intiniiii and pUnii. Be lUics thai ih« iiiti- ■nMH cuiupMttion of iniwJn it didlcall lo ikuvl in lli'i vi^ilcbnla. but that in MVLial of ihd mrcnoT>uiini!i ii iinMilily <hM-ov«reil. Tlie muKuW Abrm of Ihe cny-fli'h rr rompotcil of trsnt|KiKnl fibrillS diifOted lonf-Xudiailly, IB Dm (iilenah of whieh ihew «xitl a gtuit qiianfily of tnniparant globule pl«r>i) ifitKuIitly, uod oI]<hI by Uulrvcliel mtucaJar co'puKUi ; ht dmg- ■utr«lhii n-inu^^r:, ^filitillo-tarpuitiilar t'line. In Ihe hcnrlof ihc above kdi- idbI Ihc Hbrlllic uk: fe* in number, bnl the rorpinclM flbound -, ihg lalier ate ' aiM obKrvod lo be^ ■milled m longitudinil wttus, (uniiiog Mhui are imnicd ' arlicvUltd mittcuiif curpatcttt, latonxof llicniDlUm;a,iulhcgiidi:nHiiil, il wiu Mcrrtflincd that th« h«ut, which ii in gonenil llie moti favautsble put for micrrMcoplcal oh«rrriiiioo, ii entirHyMmpovd of afixlotnenited mincuhr cmputciti. tone ol wliicll Ivtmed longitudiaal vtie*. whilit otiien wire ^^[Cgsl«l lufp'llKr without Biiy rcgulu uril<t. We li-uiu fniin Ihis cxjimi- natioii, lh«llhe<xi!loii<s ol fiijrillai, and cvun thai of linntt organ in general, I* noi an indHpciuable condition of mutciilu motion. Thi* tsirl 1 cootidcr ibipottd&t, M M may wplain buw llm inovi-mcnl ul IhM^ annual*, lu tlw Zoopbylo. which have uo vvulcnt niuKular orgnni, a produced. Anato> inliU h»ve hithtato fctccrcd th« movtrooni tn ■ Mniraclilc <«Uulat luBue.— Sk Ruhrrckta imr Im Sirat. Imttmt de* AnimaitT tt I'tgetty*. 1
424
CAL'SB OF KRBONEUUtl ACCOUNTS,.!
immeose number of minute Eransven«e lines coidd bsi perceived crossing Uie libres, which were in some ports , divided from eucli otiier by longitudinal lines nppftrvntly marking tbc luUirai boundaries of tlic fibres ; in inos places, however, the smuU tmnsveriM.- lines were noLl separuted from eiich other by nny difitioct diTision. Several large fibres were also seen cro»siug the liacs in different directions, which appeared to consist of cellular tissue.
In reviewing the preceding statement the reader will be struck with the discrepancies it presents, and which display a humiliating exemplification of the imperfec- tion of all our tiltcmpts (o determine the inlriculu structure of the animal body. Uut much of tbiii con- tradiction I beUeve to be only apparent, depending on tlic successive improvement^ that have been made in the powers of the microscope. It is probable that physiologists, firom the time of Leeuwenhoek, have des- cribed what they really saw with iheir detective imttni- 1 1 ments; so Uiat if we reject the speculative arguments » which were founded on these imperfect observations, aV general resemblance may b« traced tlirougbout their I descriptions. Is it not, for example, probahle that Ihe'h rhomboidul vesicles of Borclli — the series of pearls ob- ' served by Hooke — tlie rounded corpuscles of the Wen- J zets, and the wrinkles noticed by Procho&ka ind Fon> •■ tuna, are io reality the identical structures discovured " by tlie powerful miscroscope of Hodgkin and Lister? .*
In concluding these remarks I sludl (|uote the follow*^ f* ing pasKOge from Uicherand, with whose opinioa<,tltB entirely coincide. " To explain tlie phenomena of r| muscular action, it is sufficient to conceive each tilire oi- ll being formed of a series of molecules of a. peculiar ,U
CELLULAR eUBSTANCB Of MCSCLK.
nature, united together by some unknown medium, whether that be ml, gluten, or any other substance but" whose fohcsion is manifeKtly kept up by the Wta] power, since the muscles yield, after death, to efforts by which, during life, they would not have been torn."
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