460 



FIG. 162. 



A. Portion of a medium-sized human muscular fibre, magnified nearly 800 diam- 

 eters. B. Separated bundles offilsrils equally magnified ; a, a, larger, and 6, 6, smaller 

 collections ; c, still smaller ; d, d, the smallest which could be detached, possibly rep- 

 resenting a single series of sarcous elements (after Sharpey). 



Although each muscular fibre may be considered to be formed 

 of a number of longitudinal fibrils, ar- 

 ranged side by side, it is also true that they 

 are not naturally separate from each other, 

 there being lateral cohesion, if not fusion, 

 of each sarcous element with those around 

 and in contact with it ; so that it happens 

 that there is a tendency for a fibre to split, 

 not only into separate fibrils, but also occa- 

 sionally into plates or disks, each of which 

 is composed of sarcous elements laterally 

 adherent one to another. 



The muscular fibres of the heart, al- 

 though striped and resembling closely 

 those of the voluntary muscles in their 

 Muscular fibres from general structure, present these distinctions : 



the heart magnified, rp, fi d f j ^ striated 



showing their cross- ', J .,, 



stria;, divisions, and tne 7 branch and anastomose one with an- 

 junctions (from KoiH- other, and no sarcolemma can be usually 

 ker). discerned (Fig. 162). 



