ANTS AND PLANTS 205 



that the most varied structures have been expressly 

 modified for the purpose of affording shelter to 

 beneficent guests, appears to me as wide of the truth 

 as to assert that the association of ants with all 

 " myrmecophilous " plants is purely accidental, sheer 

 opportunism on the part of the ants, and that none 

 of the elaborate structures of the plants are more than 

 part of their normal development. My study of 

 natural history, if it has taught me nothing else, has 

 taught me that biological phenomena will not fit into 

 Procrustean beds of theory, every case must be taken 

 on its merits, and when the honest student observes 

 that exceptions to a rule are more numerous than the 

 examples of the rule he need not be disconcerted, for 

 he will have learnt that Nature has endless ways of 

 adapting means to ends and of meeting every kind of 

 emergency. 



Note, p. 190. Polypodium carnosum. I have met with this fern 

 growing high up on the branches of very tall trees tunnelled, but 

 without an ant visible. C. H. 



