238 



THE OCEAtf WOELD. 



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 be suddenly drawn up, the lines hauled in most 

 rapidly being those near the crown of tentacles. This continuous 

 play of the lines has no other object than to attract the prey destined 



Fig. 97. Offensive apparatus of Physophora hydrostatica. 



to feed the polyp, and we cannot find any better comparison for 

 them than the fishing-lines to which they have been compared. The 

 moment that some small microscopic medusae, larvae, or crustaceans 

 come within the sphere of those redoubted lines, it is at once sur- 

 rounded, seized, and led with irresistible force towards the mouth of 

 this polyp by a gentle and gradual contraction of the line; the 

 stinging organs, complicated as we have seen them to be in the Phy- 



