On the Mechanical Conception of Nature. 647 



istence. But this does not exist variation rather 

 takes place in a fixed direction only (in Askenasy's 

 sense), and this can be nothing else than the 

 expression of an innate law of development, i.e. a 

 phyletic vital force. 



This deduction appears to me in two ways 

 erroneous. In the first place it is incorrect that 

 a quite unlimited variability is a postulate of the 

 theory of selection, and in the next place the 

 admission of variability, which is in a certain sense 

 " fixed in direction," does not necessitate the 

 assumption of a phyletic vital force. 



A mere unsettled variability, uniform in all 

 possible directions, is, according to Von Hartmann, 

 necessary for the theory of selection, because only 

 then does the variability offer a certain guarantee 

 "that under given conditions of life tl.e variations 

 necessary for complete adaptation will not be 

 wanting." But it is hereby overlooked that the 

 new life conditions to which the adaptation must 

 take place are as little fixed and unchangeable as 

 the organism itself. In such a case of transfor- 

 mation we have not to deal with a type of organi- 

 zation which was before fixed and immutable, 

 and which has to be squeezed into new life-con- 

 ditions as into a mould. The adaptation is not 

 one-sided, but mutual ; a species in some measure 

 selects its new conditions of life, corresponding 

 with those possible to its organization, i. e. with 

 the variations actually occurring. I will choose 



