General Considerations. xxv 



to genera and still hig-lier divisions, as we deal with individuals 

 in referring- them to particular species, and to believe that the 

 'secret bond' which colligates species under larger groups, is 

 of the same genealogical character as that which we look for 

 always, and often find in the case of individuals. Many of the 

 peculiarities which attach to biological classifications would thus 

 receive a reasonable explanation ; but where verification is, ex Jii/po- 

 thesi, impossible, such a theory cannot be held to be advanced out 

 of the region of probability. The acceptance or rejection of the 

 general theory will depend, as does the acceptance or rejection of 

 other views supported merely by probable evidence, upon the par- 

 ticular constitution of each individual mind to which it is presented. 

 But whether the general theory be accepted as a whole or not, it 

 must be allowed that in the face, on the one hand, of our know- 

 ledge of the greatness of the unlikeness, which may be compatible 

 with specific identity ; and, on the other, of our ignorance of the 

 entirety of the geological record, the value of the special ' Phylo- 

 genies,' or hypothetical genealogical pedigrees, reaching far out of 

 modern periods, are likely to remain in the very highest degree 

 arbitrary and problematical. 



