802 OF THE STRUCTURE AND FUNCTIONS OF MUSCULAR TISSUE. 



Schweigger-Seidel l to be composed of transversely striated oblong cells, 

 often forked at their extremities, and containing one or several nuclei ( 233, 

 Fig. 119). The divarication of the terminal portions and the occasional 

 presence of lateral processes, give rise to the illusory appearance, described 

 by Skey and others, of anastomoses occurring between the fibres. 2 The 

 length of the fibres in the Sartorius varies, according to Krause, from one- 

 third of an inch to one inch and a half; whilst, according to Dr. Nicol, 3 in 

 the small muscles of the hand they are coequal with the length of the 

 muscle, and in the muscles of the forearm vary from ^th of an inch to 

 one inch. During life the fibres of striated muscle appear to be semi-trans- 

 parent and of soft consistence. 4 After death each fibre can be split either 

 longitudinally into fibrillcB, the number of which has been estimated at six 

 or seven hundred, or transversely into a series of disks; the average diame- 

 ter of the fibrillse is ^^h of an inch in man, and they are bound together 

 by a transparent sheath, the sarcolemma (Fig. 283) 5 (between which and 

 the contractile substance is sometimes, as in the muscular fibres of the crab, 

 a distinct layer of protoplasm). On the surface of the sarcolemma and 

 sometimes in the interior of the fibre are nuclei, containing one or more 

 nucleoli, and readily brought into view by the action of acetic acid. Ac- 

 cording to some observers these are to be regarded as the remains of the 

 original cells from which the muscular fibres were developed ; others have 

 regarded them as centres from whence new muscular fibres may originate ; 

 others, as the corpuscles of the connective tissue distributed through the 

 muscle, and therefore as centres of nutrition analogous to the lacuure of 

 bone; and still more recently it has been maintained that they are in con- 

 nection with the ultimate terminations of nerves. The exact structure of 

 the fibrillse is still doubtful. Under high powers of the microscope they 



1 Strieker's Hum. and Comp. Histology, Syd. Soc. Transl., vol. i, p. 244. 



! It is usually stated that no sarcolemma exists around the cardiac- muscular fibres. 

 Winkler, however, describes it as being present in the form of an extremely delicate 

 membrane. Reichert's Archiv, 1867, p. 221. 



3 Schmidt's Jahrbiicher, Bd. cxxxii, 1866, p. 148. 



1 Kiihne (Physiol. Chemie, 1868, p. 281 ; also Marey, Kev. dos Cours Scient., tome 

 iii, p. 797) observed a Nematoid worm (Myoryctes Weissmannii), move with appar- 

 ent freedom in the interior of a fibre. The movements of the worm displaced the 

 stria?, which as it passed onward resumed their natural position. Besides this evi- 

 dence of the semifluid nature of the contents of the fibre, it has been found that when 

 a current of electricity is passed through a few muscular fibres, the substance of the 

 muscle accumulates around the negative pole, indicating a certain freedom of move- 

 ment in the constituent particles. 



6 The following authorities may also be consulted: Schwalbe, Ueber den fein. 

 Bau d. Muskelfasern wirbelloser thiere, Schultze's Archiv, Bd. v, p. 205; Ratzel, 

 Histol. Unters. Zeits. f. wiss. Zoo]., Bd. xix, p. 257; Schneider, Ueber die Muskeln 

 der Nematoden, idem, p. 284; Grenacher, Ueber die Muskelelemente von Gordius, 

 idem, p. 287; Montgomery. Zur Frage iiber die Struct, v. Contract, quergest. Mus- 

 kelfasern, Centralblatt, 1870, p. 163 ; Ran vier, Note sur la Structure intime du Tissue 

 Musculaire, in French Translation of Frey's Histology, 1870, p. :;iir,, and Comptes 

 Rendus, t. Ixxvii, 1873; Merkel. Der quergestreifte Mu'skel, Max Schultze's Archiv, 

 Bd. viii, 1872, p 244; Donitz, Beitragc zur Kenntniss der quergestreifte Mu-kelfa- 

 sern, Reichert's Archiv, 1871, p. 434; Wagener, Ueber die Querstreifen den .Muskeln, 

 Sitzungsber. d. Gesell. zur Marburg, 1872, pp. 25, 117, 141; Grumnach, Struktur 

 der Muskelfasern bei den Insekten, Centralblatt, 1872; Engelmann, Mic. Untersuch. 

 u. d. quergestreifte Muskelsubstanz, Pfliiger's Archiv, Bd. vii, pp. 33 and 155; 

 Sachs, Die querstreifte Muskelfasern, lleirhert's Archiv, 1872, p. 607; Kr:,u-e, Got- 

 ting.-n Nachrichten, Aug. 1868, p. 357; Zeits. f. Biologie, Bd. v, 1869, p. 414: and 

 Pfluger's Archiv, 1873, Bd. vii, p. 508; Floegel, Schultze's Archiv, Bd. viii, 1871, 



S 69, and Med.-Chir. Rev., 1872, p. 520; Henocque, Lancet, 1870, vol. i, p. 812 

 ensen, Arbeiten aus dem Kiel Physiolog. Institut., 1868; Dwight. Month. Mic. 

 Jour., vol. xii, p. 29. 



