MUSCULAR CONTRACTION. 



terminations of the motor nerves, or a peristaltic shortening 

 and swelling, rapidly running the length of the fibre. 



The recent experiments of Aeby, which have been repeated 

 and extended by Marey, demonstrate beyond a doubt that 

 when one extremity of a muscle is excited, a contraction occurs 

 at that point, and is propagated along the muscle in the form of 

 a wave, exactly like the peristaltic action of the intestines, ex- 

 cept that it is more rapid. Both Aeby and Marey have suc- 

 ceeded in measuring the rapidity of this wave, and find it to 

 be about forty inches per second. 1 Applying this principle 

 to the physiological action of muscles, Aeby advances the 

 theory that shortening of the fibres takes place wherever 

 a stimulus is received, and that this is propagated in the 

 form of a wave, which meets in its course another wave 

 starting from a different point of stimulation. As we know 



FIG. 18. 



Diagram of the muscular wave after Aeby. (MABEY, Du mouvement dans les fonctions 

 de la vie, Paris, 1868, p. 282.) 



that the motor nerves terminate at different points by be- 

 coming fused, as it were, with the sarcolemma, we can readily 

 comprehend, under this theory, how the simultaneous con- 

 traction of all the fibres of a muscle is produced by stimula- 

 tion of its motor nerve. This idea is expressed in the ac- 

 companying diagram. 



1 MAREY, Du mouvement dans lesfonctions de la, vie, Paris, 1868, p. 280. 



