174 



PRACTICAL ANATOMY 



the fibril is called a muscle-bead or sarcous element ; 

 it is composed of a cell of protoplasm (in the form of a 

 brick having rectangular sides), and devoid of cell-wall 

 or nucleus. A series of such beads end to end constitute 

 the fibril ; a bundle of such fibrillae (a fibre) will exhibit 



at their points of seg- 

 mentation the transverse 

 markings or lines or 

 stripes already described. 

 If the fibre be torn across 

 a plate of beads, or sar- 

 cous elements or seg- 

 ments which adhere to 

 one another by their 

 sides may be detached, 

 such a plate is called a 

 disk of Bowman, which 

 may be defined as being 

 a single plane of sarcous 

 elements adherent to one 

 another by their sides. 

 If the fibre is viewed en- 

 tire and with moderate 

 powers, it is observed to 

 present a wavy outline, 

 the convexity being be- 



FIG. 79. UNSTRIPED MUSCULAR TISSUE. tweeil the lines of SCg- 



A and B, foetal cells ; C, H, fully formed fibre ; I, , . . . . 



bundle of fibres; K, cross-section of bundle of pale mentation Or StliatlOll, 

 muscular fibres. 



and which strise are called 



the lines of Dobie. Across the convexity of the fibre a 

 clear stripe is seen described accurately by Hensen. 



The involuntary muscle consists of nucleated fusi- 

 form and spindle-shaped cells arranged in bundles, held 

 together by the perimysium. Each cell is about 





