MUSCLES. 



173 



long, and may be likened to a string of beads, each bead 

 15-^ inch thick and T T^^ inch long; a great number 



FIG. 78. MUSCULAR TISSUE. 



1, scheme of the different parts of striped muscular fibre ; S, sarcolemma ; K, nucleus ; 

 2, striation ; F, fibrillse : N, nerve : E, nucleated nerve-plate ; 2, part of a cross-section ; 3, 

 isolated fibrillae : 4, highly magnified fibril of insect muscle; A, Krause-Amici's line; B, 

 anisotropic substance ; C, central disk ; D, isotropic substance ; 5, separation of disks ; 6, 

 cell of heart-muscle of frog; 7, embryonal development of muscular fibre; 8, cells of heart- 

 muscle; 9, cross-section of heart-muscle; 10, unstriped muscle-cells; 11, cross-section of 

 unstriped muscle-cells ; 12, muscular fibre with tendon ; 13, interfibrillar muscular nerves. 



of such flbrillae make up a fibre which necessarily exhibits 

 the transverse striae due to the division of the fibril into 

 the separate segments or beads. A single segment of 



