194 



ON THE ELEMENTARY PARTS OF THE HUMAN FABRIC. 



series of particles, which may be termed primitive particles or sarcous ele- 

 ments, the union of which constitutes the mass of the fibre. These elementary 



[Fig. 95. 



Fragments of Striped Elementary Fibres, showing a cleavage in opposite directions; magnified 300 

 diameters; 1, longitudinal cleavage; the longitudinal and transverse lines are both seen ; some longitu- 

 dinal lines are darker and wider than the rest, and are not continuous from end to end ; this results from 

 partial separation of the fibriHEe ; 6, fibrilloe, separated from one another by violence at the broken end 

 of the fibre, and marked by transverse lines equal in width to those on the fibre ; 7, 5 represent two ap- 

 pearances commonly presented by the separated single fibrilla, (more highly magnified ;) at 7 the borders 

 and transverse lines are all perfectly rectilinear, and the included spaces perfectly rectangular; at 8 the 

 borders are scalloped, the spaces bead-like ; when most distinct and definite, the fibrilla presents the 

 former of these appearances ; 2, transverse cleavage ; the longitudinal lines are scarcely visible ; 3, in- 

 complete fracture following the opposite surfaces of a disc, which stretches across the interval and re- 

 tains the two fragments in connection ; the edge and surface of this disc are seen to be minutely granular, 

 the granules corresponding in size to the thickness of the disc, and to the distance between the faint 

 longitudinal lines; 4, another disc nearly detached; 5, detached disc more highly magnified, showing the 

 sarcous elements.] 



particles are arranged and united together in the two directions. All the re- 

 sulting discs, as well as fibrillae, are equal to one another in size ; and con- 

 tain an equal number of particles. The same particles compose both. To 

 detach an entire fibrilla, is to abstract a particle of every disc; and vice versa." 

 227. The elements of Muscular Fibre are bound together, in the perfect 

 condition of the fibre, by a very delicate tubular sheath. This cannot always 

 be readily brought into view; but it is occasionally seen with great distinct- 

 ness : thus, when the two ends of a fibre are drawn apart, its contents will 



sometimes separate without the rupture 

 of the sheath, which then becomes evi- 

 dent ; and this, during the act of con- 

 traction, may sometimes be observed 

 to rise up in wrinkles upon the surface 

 of the fibre, as seen in Fig. 100. This 

 sheath is quite distinct from the areolar 

 tissue, which binds the fibres into fasci- 

 culi; and it has been termed, for the 

 Its existence may be demonstrated 



Fig. 96. 



Fibre of Human Muscle broken across; the 

 fragments connected by the untorn Myolemma. 



in 



sake of distinction, the Myolemma. 

 any Muscular fibre, by subjecting it to the action of lluids, which occasion a 

 swelling of its contents ; this is especially the effect of acids and alkalies, and 

 may be well produced by the citric and tartaric acids, and by potash. For a 

 time, the Myolemma yields to the distention which takes place from within; 

 but at last it bursts at particular points, and a sort of hernia of its contents 

 takes place, making the existence of a perfect envelope in all other parts quite 



