1 88 THE SUCCESSION OF ANIMAL FORMS 



imperfection of the record, or to the movements or migrations 

 of species. The record is now, in many important parts, too 

 complete, and the simultaneousness of the entrance of the 

 faunas and floras too certainly established, and moving species 

 from place to place only evades the difficulty. The truth is 

 that such hypotheses are at present premature, and that we 

 require to have larger collections of facts. Independently of 

 this, however, it appears to me that from a philosophical point 

 of view it is extremely probable that all theories of evolution, as 

 at present applied to life, are fundamentally defective in being 

 too partial in their character; and perhaps I cannot better group 

 the remainder of the facts to which I wish to refer than by 

 using them to illustrate this feature of most of our attempts at 

 generalization on this subject. 



First, then, these hypotheses are too partial, in their tendency 

 to refer numerous and complex phenomena to one cause, or to 

 a few causes only, when all trustworthy analogy would indicate 

 that they must result from many concurrent forces and deter- 

 minations of force. We have all, no doubt, read those ingenious, 

 not to say amusing, speculations in which some entomologists 

 and botanists have indulged with reference to the mutual 

 relations of flowers and suctorial insects. Geologically the 

 facts oblige us to begin with Cryptogamous plants and chewing 

 insects, and out of the desire of insects for non-existent honey, 

 and the adaptations of plants to the requirements of non- 

 existent suctorial apparatus, we have to evolve the marvellous 

 complexity of floral form and colouring, and the exquisitely 

 delicate apparatus of the mouths of haustellate insects. Now, 

 when it is borne in mind that this theory implies a mental con- 

 fusion on our part precisely similar to that which, in the depart- 

 ment of mechanics, actuates the seekers for perpetual motion, 

 that we have not the smallest tittle of evidence that the changes 

 required have actually occurred in any one case, and that the 

 thousands of other structures and relations of the plant and the 



