VIII. 



MUSCLE-TISSUE. 



MUSCLE, the motor apparatus proper, is a formation of 

 living matter . in a reticular arrangement. The points of 

 intersection in smooth muscle are irregularly scattered ; in 

 striated muscle, they are arranged with great regularity in the 

 so-called sarcous elements. The connecting filaments are ex- 

 tremely delicate, allowing slow but, considering the bulky forma- 

 tions of muscle, powerful contractions of the living matter. 



Muscle is constructed on the plan of an amoeba, or that of 

 any other plastid. The difference is that the points of inter- 

 section of the living matter in the amoeba are small and irregu- 

 larly distributed, while in muscle the nodules of the reticulum 

 are large and more or less regular in their arrangement. The 

 fluid contained in the meshes of the reticulum in the amoeba 

 corresponds to the muscle fluid between the rows of sarcous ele- 

 ments. Contractility is inherent in the amoeba and every plas- 

 tid; therefore, also in muscle, independently of nervous influence. 

 The independent contractility of muscle was proved by J. Miiller, 

 in 1834, after division of the nerves, and by Claude Bernard, in 

 1857, after abolishing the action of the motor nerves by curara. 

 The enlargement of the nodules of living matter, the shortening 

 of the connecting filaments, and the narrowing of the mesh- 

 spaces produces the contraction in the amoeba, as well as in the 

 muscle (see page 29). The difference is that, while in the amoeba 

 one portion of the body is in contraction, the other, on the con- 

 trary, in extension : in all highly developed animals one muscle, 

 or a group of muscles, is in the state of contraction, while 



