240 
THE OCEAN WORLD. 
with extremely long and delicate rootlets reaching the bottom of the 
vase. But in the case of the Physophora the living roots are in con- 
tinual motion. Each line is elongated, foreshortened, and contracted 
in a thousand ways. The least movement of the water causes the 
stinging capsules to he suddenly drawn up, the lines hauled in mos 
rapidly being those near the crown of tentacles. This continuous 
play of the lines has no other object than to attract the prey destine 
Fig. 97. Offensive apparatus of rhysopliora hydrostutica. 
to feed the polype, and we cannot find any better comparison 
them than the fishing-lines to which they have been compared. g 
moment that some small microscopic medusa 1 , larvae, or crustacean 
come within the sphere of those redoubted lines, it is at once s ^ 
rounded, seized, and led with irresistible force towards the mouthy 
this polype by a gentle and gradual contraction of the line , 
stinging organs, complicated as we have seen them to he in the P 1 
