342 EVOLUTION, OLD AND NEW. 



or of attack in relation to such and such another 

 species ; of a longer neck and longer legs, or of what- 

 OTer other modification the gradually changing cir- 

 cumstances may be rendering expedient. It is easy to 

 understand the accumulation of slight successive modi- 

 fications which thus make their appearance in given 

 organs and in a set direction. 



With Mr. Darwin, on the contrary, the variations 

 being accidental, and due to no special and uniform 

 cause, will not appear for any length of time in any 

 given direction, nor in any given organ, but will be 

 just as liable to appear in one organ as in another, and 

 may be in one generation in one direction, and in 

 another in another. 



In confirmation of the above, and in illustration of 

 the important consequences that will follow according 

 as we adopt the old or the more recent theory, I would 

 quote the following from Mr. Mivart's 'Genesis of 

 Species.' 



Shortly before maintaining that two similar struc- 

 tures have often been developed independently of one 

 another, Mr. Mivart points out that if we are dependent 

 upon indefinite variations only, as provided for us by 

 Mr. Darwin, this would be " so improbable as to be 

 practically impossible." * The number of possible varia- 

 tions being indefinitely great, " it is therefore an inde- 

 finitely great number to one against a similar series of 

 variations occurring and being similarly preserved in 

 any two independent instances." It will be felt (as 

 Mr. Mivart presently insists) that this objection does 

 ♦ ' Genesis of Species,' p. 74, 1871 



