SECTION OF COVERED-EYED MEDUSA. 



G7 



bell, the result being, at each discharge, two con- 

 traction waves, which start at the same instant, 

 one on each side of the ganglion, and which then 

 course with equal rapidity in op])osite directions, 



mm' m 



Fig. 9. 



and so meet at the point of the disc which is 

 opposite to the ganglion. Suppose, now, a number 

 of radial cuts are made in the disc according to 

 such a plan as this (Fig. 9), wherein every radial 

 cut deeply overlaps those on either side of it. The 



