OF MOVEMENT IN ANIMALS. 



35 



phases vary under the different influences which we have just 

 described. 



If we endeavour to pursue the study of this phenomenon of 

 the contraction of the muscle, we see that it is only a change 

 in the form of that organ, and that the diminution of length 

 is accompanied by a corresponding dilatation which might 

 be expected in a sensibly incompressible tissue. But the 

 manner in which this dilatation is produced is curious. 



Fig. 5. — Successive transformations of the shock of a muscle becoming 

 gradually poisoned by veratrine. Underneath to the left of the figure 

 are shown the first effects of the poison. 



It has been long since observed that there are formed upon 

 living muscles at the points where they are excited, lumps or 

 nodosities which run along the whole length of the muscle, 

 with more or less rapidity, like a wave on the surface of the 

 water. Aeby"^' has shown that this is a normal phenomenon, 

 and, under the name of muscular wave, he has described this 

 movement, which, from the excited point, passes to the two 

 extremities of the muscle at the rate of about a metre in a 

 second. By means of an apparatus, which we have called 



* Untersuchungen iiber die Fortpflanzungsgeschivindiqkeit der Reizitngs in 

 der querzgestreiften Muskelfasern, Braunschweig : 1862. 



