220 PHYSIOLOGY AND MORPHOLOGY OF ANIMALS. 



cular tissue it has connective tissue to web it together, 

 nerves to stimulate it, and blood vessels to nourish it. 



Kinds. — There are two kinds of muscle — voluntary 

 and involuntary — differing from one another in many 

 respects, (a) The one is found on the exterior, the other 

 in the interior of the body, {b) The one is red, the other 

 is white, (c) The fibers of the one are transversely stri- 

 ated, of the other are non-striated, (d) The nerve supply 

 of the one is largely from the conscio-voluntary system, 



of the other from the reflex 

 system, (if) In the voluntary 

 muscle the fibers are massed 

 into a distinct organ, having 

 a distinct name, and all co- 

 operate through a tendon to 

 produce one motion ; while 

 the involuntary muscle exists 

 in sheets of parallel fibers, 

 surrounding hollow organs 

 (stomach, intestines, bladder, 

 etc.), has no tendon, and the 

 fibers do not contract co- 

 operatively, but consecutively, 

 by a contraction propagated 

 from fiber to fiber. (/) The 

 Fig. 141.— Muscular fibers of the voluntary muscles contract 

 (ifte r °Ken h t0 embryO ""^ quickly and powerfully, the 

 involuntary slowly and fee- 

 bly, (g) Lastly, the voluntary are attached to the skele- 

 ton, while the involuntary are not attached to the skele- 

 ton, but surround hollow organs. 



There are some muscles, however, which are inter- 

 mediate. The most striking case is the heart. The 

 muscle of the heart is red, transversely striated, and 

 contracts powerfully, and yet it is /^voluntary, consists 



