94 OF THE MUSCLES. 



mach, intestines, bladder, uterus, &c. They are purely of 

 a white hue ; and are put in motion entirely by mechani- 

 cal means, that is by the amount or condition of their con- 

 tents. Of this last description of muscle we shall have to 

 speak more at length when discussing the various organs to 

 W'hich it appertains. 



That which is, however, generally understood by a muscle, 

 is a distinct body, having- a determinate action. The vascu- 

 larity of muscles is extreme ; and their power is connected 

 with the blood which circulates w^ithin them ; for when de- 

 prived of a part of it, they become weak ; and if it be 

 wholly lost, they will die, or lose all their force. On the 

 contrary, by exertion, which is but another term for increased 

 vascularity, since motion forces more blood into them, they 

 enlarge in size, in strength, and colour. Thus a limb which 

 has lost its feeling, and is freed from the control of the will, 

 may by continued artificial motion be made to retain its 

 original hue and bulk. From the extreme vascularity of 

 muscles, their powers are very great ; they are also plenti- 

 fully supplied with nerves and absorbents. They sympathize 

 greatly with other parts ; and other parts with them ; thus 

 if a muscle be greatly injured, the head, stomach, heart, 

 bowels, &c. are disordered ; and if another important struc- 

 ture be hurt the muscles assume a disordered condition : 

 few persons, during severe illness, being disposed to move 

 W'ith alacrity. Nevertheless muscles possess their peculiar 

 faculty ; which is to contract or shorten, and thereby pull 

 closer any loose part into which they or their tendons may 

 be inserted. During contraction, they become thicker and 

 harder ; and alter their shapes, but do not increase in bulk. 

 This power is dependent on the will in muscles, which are 

 termed voluntary ; and in the involuntary on appropriate 

 stimulus, as light to the iris. This obedience to the action of 

 stimuli has been called their irritability ; and exists for some 

 time after death. If, however, the nerves going to voluntary 

 muscles are pressed upon or tied, they lose their power 

 of motion, or become incapable of obeying the commands 

 of the will : hence it w^ould appear, that nervous influence 

 is the proper stitmilus, for the performance of their inherent 

 functions, to voluntary muscles. Neither can the will force 

 the muscles to contract beyond the capacity of their physical 



