THE "GENERAL MORPHOLOGY" 247 



corresponds to what we regard as the individual 

 man, combine and form a new body, a social 

 individual. As citizens of this new state they 

 have introduced the most rigid division of labour. 

 One medusa does nothing but eat, and it thus 

 provides nourishment for the rest, as they are all 

 Joined in one body. Another accomplishes the 

 swimming movement ; another has been converted 

 entirely into a reproductive organ. In a word, 

 the whole has become a '^ unity " once more, 

 equipped with its various organs like any large 

 body. Sometimes thousands of separate medusas 

 enter into the structure of one of these wonders 

 of the deep. And as each of the medusae is 

 generally a very pretty, flower-like creature, the 

 social groups with their charming colours look 

 like floating garlands of flowers made of trans- 

 parent and tinted crystal. Their beauty would 

 soon fix Haeckel's attention, but their bearing on 

 his theory of individuality would give them an 

 even greater value. For several years he had 

 searched most attentively in the animal world for 

 these '^ over-individuals " of the highest class. In 

 the morphology he had had to be content with 

 an old illustration of something of the kind, the 

 star-fish. It was supposed to be a combination 

 of vermalians. In this case the hypothesis has 

 broken down, though there was a good deal to be 

 said for it at first, and it was abandoned by him 

 afterwards. But now, when he saw enormous 

 numbers of siphonophores in the animal streams 

 at Lanzarote, he entered upon a decisive study of 



