SECRETS OF THE OCEAN 153 



like bunches of currants, and later will break off 

 and swim around at pleasure in the water. Occa- 

 sionally one is fortunate enough to discover these 

 small jellies in a pool where they can be photo- 

 graphed as they pulsate back and forth. When 

 these attain their full size they lay eggs which 

 sink to the bottom and grow up into the plant-like 

 hydroids. So each generation of these interesting 

 creatures is entirely unlike that which immedi- 

 ately precedes or follows it. In other words, a 

 hydroid is exactly like its grandmother and grand- 

 daughter, but as different from its parents and 

 children in appearance as a plant is from an ani- 

 mal. Even in a fairy-story book this would be 

 wonderful, but here it is taking place under our 

 very eyes, as are scores of other transformations 

 and " miracles in miniature" in this marvellous 

 underworld. 



Now let us deliberately pass by all the attrac- 

 tions of the middle zone of tide-pools and on as 

 far as the lowest level of the water will admit. 

 We are far out from the shore and many feet 

 below the level of the barnacle-covered boulders 

 over which we first clambered. Now we may 

 indeed be prepared for strange sights, for we are 

 on the very border-land of the vast unknown. The 

 abyss in front of us is like planetary space, un- 

 known to the feet of man. While we know the lat- 

 ter by scant glimpses through our telescopes, the 

 former has oaly been scratched by the hauls of 



