318 STRUCTURE OF MUSCULAR TISSUE. [BOOK I. 



The blood-vessels of striated muscular tissue are 

 vessels of very abundant, and the capillaries are small. The 



muscular latter are distributed upon the fibres, in elongated 



tissue. meshes ; but they nowhere pierce the sarcolemma. 



The capillaries of the red variety of voluntary muscles are wider 

 than those of the pale. They are disposed in shorter meshes, and are 

 marked by peculiar aneurismal dilatations 1 . 



The structure of the Muscular Substance of the Heart. 



The third kind of muscular tissue consists of quadrate cells with a 

 faint longitudinal striation and a rough transverse striation. In the 

 centre of each cell is an oval nucleus, usually associated with a 

 small amount of granular protoplasm ; and not unfrequently the cell- 

 substance contains a few scattered fat particles. The cells are joined 

 end to end, or side to side, and often by means of stout truncated 

 processes. They are apparently destitute of sarcolemma. 



The heart-muscle of amphibia differs somewhat from the above 

 description. The cells are not quadrate, but spindle-like, overlapping 

 the neighbouring cells. They are transversely striated; and both 

 Krause's membrane and Hensen's disc are said to have been seen 2 . 

 The dark striae are doubly refracting. 



In mammals the size of the cells is from 50 70 //, long by 

 15 23 Abroad 3 . 



Terminations of Nerves in Muscle. 



The mode of union of muscles and motor nerves cannot as yet 

 be said to have acquired more than anatomical significance. The cells 

 of smooth muscle are entangled in a net of nervous fibres, from which 

 fine offsets seem to end abruptly on the surface or in the substance 

 of the cells, or even to pierce the nuclei 4 . 



A similar disposition of nerves has been claimed for the heart- 

 muscle 5 . 



In the case of striated voluntary muscle, the medullated nerve 

 fibres reach the sarcolemma, and pierce it. The sheath of Schwaim 

 or neurilemma becomes continuous with the sarcolemma. The 



1 Ranvier, "Note sur lee vaisseaux sanguins et la circulation dans les muscles 

 rouges." Op. cit., p. 446. E. Meyer, loc. cit. 



2 Langerhans, "Zur Histologie des Herzens," Virchow's Archiv, Vol. LVIII. p. 56 

 Gerlach, L., "Ueber die Nervenendigung in der Musculatur des Froschherzens." 

 Virchow's Archiv, Vol. LXVI. p. 187. 



3 Schweigger-Seidel, "DasHerz," Strieker's Handbuch, chap. vii. p. 179. 



4 Consult Arnold, "Gewebe der organischen Muskeln," Strieker's Handbuch, chap, 

 iv. p. 144; and, of the more recent authorities, Lb'wit, Wien. Acad. Sitzungsb. in. 

 Abth., Vol. LXXI. 1875, p. 355. Gscheidlen, R., Arch. /. mikr. Anut., Vol. xiv. p. 321. 

 Ranvier, Comptes Eendus, Vol. LXXXVI. p. 1142. 



5 Consult Schweigger-Seidel, Strieker's Handbuch, chap. vii. ; and also P. Langerhans, 

 Virchow's Archiv, Vol. LVIII. p. 65. L. Gerlach, Virchow's Archiv, Vol. LXVI. p. 187. 

 E. Fischer, Arch. f. mikr. Anat., Vol. xm. p. 365. 





