90 JELLY-FISH, STAR-FISH, AND SEA-URCHINS. 



now stimulating the end a, or on watching the 

 lithocyst there discharge, the resulting contraction- 

 wave would be observed to bifurcate at h, and then 



pass on as two separate waves through the zones, 

 h c,b d. Now, as these two waves were started at 



