108 



HITCHCOCK'S ANATOMY 



A View of the Fragments of Striped elementary Fibers, showing a cleavage in opposite 

 directions — magnified 300 Diameters. 1, The Longitudinal Cleavage. 2, The Transverse 

 Cleavage, the Longitudinal Lines being scarcely visible. 3, Incomplete Fracture, follow- 

 ing the opposite surfaces of a Disc which stretches across the Interval and retains the two 

 Fragments in connexion. 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 dis- 

 tance between the faint Longitudinal Lines. 4, Another Disc nearly detached. 5, A de- 

 tached Disc more highly magnified, showing the Sarcous Elements. 6, Fibrillar separated 

 by violence from each other at the broken end of the Fiber. 7, 8, The two appearances 

 commonly presented by the separated single Fibrillae ; more highly magnified, at 7 the 

 spaces are rectangular, at 8 the borders are scalloped and the spaces bead-like. 



of an inch, and number about 650 in each ultimate fiber. 

 They are unprotected by any covering, while both the fasicu- 



Fm. 122. 



lus and ultimate fiber 

 are everywhere pro- 

 tected by a delicate 

 sheath called the 

 Sarcolemma. 



230. Organic, or 

 Unslriped, and Ani- 

 mal, or Striped Fi- 

 bers. — All the mus- 

 cles of the body are divided into two classes, according to 

 their function. Those necessary for carrying on the vital 

 functions, such as breathing and digestion, are called Or- 

 ganic, and those under the control of the will Animal Fi- 

 bers. In addition to their use as a means of distinction, 

 they may be known by their appearance under the micro- 



Fibrils of Human Muscle. 



What is the Sarcolemma ? On what element of muscle is this wanting? 230. Give 

 the two functional classes of the muscles. 



