The Wonder of the World 21 



So, on a larger scale, we see in racial evolution 

 the twofold aspect of flux and continuity, of change 

 and persistence, of deviation and inertia, of vari- 

 ation and hereditary resemblance. Alle Gestalten 

 sind dhnlich, und keine gleichet der andern. Hux- 

 ley put the point with his usual vividness: " Flow- 

 ers are the primers of the morphologist; those who 

 run may read in them uniformity of type amidst 

 endless diversity, singleness of plan with complex 

 multiplicity of detail. As a musician might say: 

 every natural group of flowering plants is a sort of 

 visible fugue wandering about a central theme 

 which is never forsaken, however it may, mo- 

 mentarily, cease to be apparent." ("Life of 

 Owen," Vol. II, p. 288.) 



In the relatively small group of Alcyonarian 

 corals, with which we happen to be particularly fa- 

 miliar, the general plan of structure is exceedingly 

 simple — polyps give off stolons from which other 

 polyps arise and the colony is supported by some 

 sort of skeleton — but the heterogeneity of detail and 

 of beautiful architectural device beggars description. 



Even within the same species we can often get 

 the same impression of "a sort of visible fugue 

 wandering about a central theme.*' Take, for 

 instance, the beautiful series of three dozen or so 

 distinct varieties of the common snail. Helix al- 

 ternata, say, as they are displayed in the Ameri- 

 can Museum of Natural History. As Mr. Fran- 



