THE LIMBS 



159 



skin, giving the external form to the animal, and con- 

 stituting what is commonly called its flesh. 



Muscular tissue is composed of a great number of 

 exceedingly minute parallel fibres of peculiar structure, 

 and it differs from all other tissue in possessing the 

 property of contracting in length (with corresponding 

 dilatation in width) on the application of a stimulus, 

 usually conveyed to it through the nerve the terminal 

 fibres of which are distributed through it. The electric 

 current, or mechanical irritation, will act as a stimulus 

 to contraction, but in the living state the will of the 

 animal, conveyed from the brain along the nerve to the 

 muscle, is the usual cause of action. If the nerve is 

 divided anywhere in its course between the brain and 

 the muscle the latter will no longer act in obedience to 

 the will, and is said to be paralysed, although it does 

 not really lose its power of contraction, as may be 

 proved by the application of any other appropriate 

 stimulus either directly to the muscle or to the lower 

 part of the divided nerve. 



In order that muscles by their contraction may 

 produce movements, they must be fixed by their two 

 extremities to two different bones, which are connected 

 to each other by a movable joint. When the contrac- 

 tion brings the ends of the muscle nearer together than 

 they were before the bones must follow, and their posi- 

 tion in relation to one another must be changed. It 



