228 



NATURE 



[Jan. 1 8, 1872 



whether nerves do ever terininate in plexuses or meshes 

 of any kind. 



The fibre of voluntary muscle is said to consist of a 

 lar^e number of extremely fine filaments enclosed in a 

 transparent, homogeneous, elastic (the composition agrees 

 vi-ith that of elastic tissue), tubular sheath, called the 

 sarcolemma or myolemma, in which are nuclei, called 

 muscle-corpuscles. It might, however, be more correct to 

 say that this fibre consists of a mass of soft granular 

 matter (the granules being the sarcoiis elements of Bow- 

 man), agreeing in the main with the granular core of the 

 ganglionic cells and peripheral nerve-organs, enclosed in 

 the sheath which has been described ; for the contents of 

 the fibre, instead of splitting up longitudinally into fila- 

 ments, may split up horizontally into discs — may split cither 

 way or any way, in fact, as they would do if they were 

 made up, neither of fibrils nor discs, but of granules which 

 may, as it happens, aggregate into fibrils or discs. The 

 fibre of involuntary mui^cle, on the other hand, is made 

 up of elongated fibre-cells, connected together by ahomo- 

 geneous, transparent uniting medium, without any sarco- 

 lemma. Each of thc^e fibre-cells has a core of finely 

 granular matter, sometimes arranged so as to form imper- 

 fect fibrils, and of a distinct cell-membrane, with nuclei, 

 the shape of the cell being fusiform, with ends sometimes 

 pointed, .'sometimes truncated, sometimes simple, some- 

 times branched. The cell- membrane in reality takes the 

 place of the sarcolemma, for each cell is nothing more or 

 less than a rudimentary fibre. Indeed, in long voluntary 

 muscles there are fibres which seem to partake somewhat 

 of the character of voluntary and somewhat of the charac- 

 ter of involuntary fibres— fibres which, instead of running 

 continuously from one end of the muscle to the other, are 

 made up of several elongated fusiform cells, overlapping 

 each other at the ends, and which therefore may con- 

 sist of cell-membrane and sarcolemma both. Nor is the 

 connection of the neri'cs with the muscular fibres or cells 

 peculiar. Beale and Kolliker think that the nerves be- 

 longing to voluntary muscle end in meshes of pale fibres 

 outside the sarcolemma. Rouget, Kiihne, and others are 

 of opinion that this ending is in peculiar organs— motorial 

 end-plates continuous with the axis-cylinder of the nerve, 

 oval or irregular in shape, within the sarcolemma and 

 between it and the proper muscular substance, the primi- 

 tive nerve-sheath fusing with the sarcolemma, and one end- 

 plate being devoted to each muscular fibre. And thus it 

 maybe that the muscular fibre or cell mayagree in structure 

 with the ganglionic cell, and the peripheral nerve organ, in 

 having a soft granular core, with which one or more nerve- 

 fibres are connected, and an investing membrane of con- 

 nective tissue with one or more nuclei. It may be, indeed, 

 that the muscular fibre and cell are only varieties of the 

 peripheral nerve-organ. 



The nerve-fibres by which these several bodies — gan- 

 glionic cells, peripheral nerve organs of various kinds, 

 and muscular fibres and cells— are connected together, are 

 of two kinds, the tubular, which are while with dark 

 borders, and those which are grey, pale, non-meduUated 

 or gelatinous. The white or tubular filares, when quite 

 fresh, appear perfectly homogeneous like thre. ds of glass, 

 but afterwards, when coagulation has taken place, they 

 are found to consist of an axis, or primitive band, as it is 

 called, a white medullary coating strongly refractive of 

 light, and giving them the appearance of having dark 

 borders, and an outer membranous sheath or tube, with 

 nuclei in it, agreeing in composition with elastic tissue, 

 and being analogous to the sarcolemma. The grey, pale, 

 gelatinous fibres would seem to consist of the axis or primi- 

 tive band of the others, with obscure sheaths in which 

 are nuclei, but without medullary coating. They be- 

 long chiefly to the ganglionic system, but not exclusively ; 

 at all events the finer subdivisions of the white dark-bor- 

 dered nerves of the other systems are found to have lost 

 their dark borders, and to have become undistinguishable 



from those which have no dark borders naturally. In 

 nerve-fibres, therefore, as in nerve-cells, there would seem 

 to be a central core, and a membranous investment con- 

 taining nuclei ; and, all things considered, the connection 

 of these fibres with ganglionic cells, wiih peripheral 

 nerve-organs, and with muscular fibres and cells, would ^ 

 appear to be by one and the same method, the axis or 

 primitive band being continuous with the central soft 

 granular core of the central and peripheral elements of 

 the nervous system, and of the muscular fibres and cells 

 (for with so many points of analogy it is difficult not to 

 believe with Rouget, Kiihne, and others who agree with 

 them in this matter), the primitive sheath, when there is 

 one, being continuous with the membranous investment 

 of this core, neurilemma, sarcolemma, or other, as the 

 case may be. 



Instead of being peculiar, therefore, the voluntary mus- 

 cular fibre may be no more than a modified form not only 

 of the contractile cell of the involuntary muscular fibre, 

 but also of the nerve-fibre, and of the central and peri- 

 pheral cell-elements of the nervous system. The same 

 type of structures is to be traced out in each case. There 

 is in each case the same central, granular, soft, substance, 

 but slightly changed protoplasm prob.ibly, in the mole- 

 cular change of which an electrical change may origi- 

 nate. There is in each case outside this central sub- 

 stance a membrane which may become charged leyden- 

 jar-wise as the neurilemma and sarcolemma are supposed 

 to be charged. And, therefore, it is not aliogither beg- 

 ging the question to conclude that in each case one and 

 the same electrical law may bear rule. 



And certainly the adoption of this idea is calculated to 

 elucidate much that is obscure in the structure and action 

 of the nervous and muscular systems. 



Upon this view a use is found for the contents and 

 walls of the fibres and cells of which the nervous and 

 muscular systems are made up. The contents are wanted 

 for the generation of the charge ; the walls are wanted 

 for receiving and holding this charge. Their leyden-jar 

 office, indeed, explains why it is that the nervous and 

 muscular systems should be made up of cells and fibres. 



Upon this view one use is found for the nucleus in the 

 walls or sheath of cell or fibre. The nucleus may repre- 

 sent the spot at which the development of this wall or 

 sheath is arrested — the spot at which the original, moist, 

 conducting protoplasmic matter is not trans.'^ormed by 

 drying, or in some other way, into non-conducting wall or 

 sheath, and, therefore, as I think, the nucleus may have 

 a very definite function to fulfil. As 1 think, indeed, the 

 case may be this : that the molecular changes in which 

 the charge of the cell or fibre originates (those in the con- 

 tents of the cell or fibre) depend upon the continual ingress 

 of fresh and egress of used-up aerated matter ; that this 

 ingress and egress is, not through the wall or sheath any- 

 where or everywhere, but only through the nucleus ; that 

 the one charge not wanted for charging the inner surface 

 of the wall or sheath may escape to earth through the 

 nucleus ; and that the channel of the discharge which 

 happens when the cell or fibre passes from the state of 

 rest into that of action may also be through the nucleus. 

 Without such opening as may be supposed to exist in the 

 nucleus, indeed, it is difficult to understand how the cell 

 or fibre should be charged and discharged ; and thus, 

 upon the view in question, a use is found (not the only 

 use, of course), for the nuclei present in the walls of the 

 cells and in the sheaths of the fibres of the nervous and 

 niMscular systems. 



Upon this view, too, the infinite number of these cells 

 and fibres may in some degree be accounted for. For 

 may it not be that each cell and fibre acts as a condenser to 

 every other cell or fibre, so that a charge or discharge 

 which is feeble without being multiplied becomes anything 

 but feeble when multiplied .'' And may not this function of 

 a condenser be the one function of the Pacinian bodies .'' 



