208 ANIMAL PEDIGREES 



being cleverly effected so as to leave the original 

 kitten unaltered in the middle, and fully exposed 

 to view the whole time. 



The above examples, selected almost haphazard, 

 will suffice to illustrate the Theory of Recapitulation. 

 The proof of the theory depends chiefly on its 

 universal applicability to all animals, whether high 

 or low in the zoological scale, and to all their parts 

 and organs. It derives also strong support from 

 the ready explanation which it gives of many 

 otherwise unintelligible points. 



Of these latter, familiar and most instructive 

 instances are afforded by rudimentary organs i.e., 

 structures which, like the outer digits of the horse's 

 leg, or the intrinsic muscles of the ear of a man, 

 are present in the adult in an incompletely developed 

 form, and in a condition in which they can be of 

 no use to their possessors ; or else structures which 

 are present in the embryo, but disappear completely 

 before the adult condition is attained; for example, 

 the teeth of whalebone whales or the gill-slits 

 present in the neck during the embryonic phases of 

 all higher vertebrates. 



Natural selection explains the preservation of 

 useful variations, but will not account for the for- 

 mation and perpetuation of useless organs, and 

 rudiments such as those mentioned above would be 

 unintelligible but for Recapitulation, which solves 

 the problem at once, showing that these organs, 

 though now useless, must have been of functional 

 value to the ancestors of their present possessors, 

 and that their appearance in the ontogeny of 



