66 THE WONDER OF LIFE 



of the type she seems, so careless of the single life ' ; for 

 here we have cannibalism in the cradle, the struggle for 

 existence at the very threshold of lif e. 



In the pool where we gathered the Purpura capsules, we 

 may see the beautiful Tubularians, e.g. Tubularia indivisa, 

 waving their tentacles, and it is interesting to remember that 

 in the ovary of Tubularia, as in that of the freshwater 

 Hydra, there is a struggle for existence among the numer- 

 ous possible eggs. A few survive in Tubularia, one sur- 

 vives in Hydra ; it is a case of engulfing the other ova. 

 Thus we see how wide the conception of the struggle for 

 existence really is that it applies even to the germ-cells ; 

 and our thoughts pass on to Weismann's daring speculation 

 that there may be a struggle between the ancestral con- 

 tributions which make up the inheritance within the egg. 



Speaking of { infantile mortality ' leads us naturally 

 to think of the various ways in which it is lessened. These 

 show an interesting parallelism with rational methods in 

 operation in mankind. The first method is to transport the 

 delicate young lives from the rough-and-tumble life of the 

 seashore to the open water. Starfishes, sea-urchins, and 

 their allies, many worms of diverse kinds, many crustaceans 

 and molluscs have delicate larvae, altogether unsuited to 

 stand the hard conditions of the shore, but admirably 

 suited for a period of pelagic swimming or drifting. It is 

 true enough that Death often finds them there also, but 

 they are certainly much safer than near the shore. 



It is an interesting question whether the pelagic habit 

 of the larvae of some shore animals is an indication that 

 the cradle of the stock to which they belong was the open 

 sea, just as the littoral habit of the robber-crab's young 

 is an indication of the original shore home of this terrestrial 



