Like all sedentary marine animals, it solved the 

 food problem by the simple method of living upon 

 whatever morsels the currents brought within its 

 circumscribed compass. With its wants thus sup- 

 plied, it is unlikely that it was moved solely for 

 the sake of sustaining itself to leave its attach- 

 ment. But it would seem that the requirements of 

 reproduction eventually were not so easily to be 

 met. The same law of chance which furnished it 

 with food was not so favorable in supplying the 

 demands which arose for a mate. Opportunities 

 for cross-fertilization apparently growing scarce, 

 the flatworm at this conjuncture circumvented the 

 threatened disaster to the further progress of its 

 species by going into action. It created newer op- 

 portunities, in fact, by beginning to crawl, and 

 perhaps by learning to swim. And with the escape 

 from this sedentary bondage, came another sort of 

 freedom : it is not improbable that, previous to this 

 precarious stage in its history, the individual could 

 reproduce by self-fertilization — a retrograde but 

 a necessary resort in order to carry on until that 

 more opportune day of emancipation. And in be- 

 coming sexually distinct in its functions, if not in 

 its form, it became, so to speak, the first many- 



[183] 



