BITKESSIBILITY OF ORGANISMS. 307 



arc merely asked to point out a conceivable mode. On the 

 other hand, they ask, not simply for a conceivable mode, 

 but for the actual mode. They do not say Show us how 

 this may take place ; but they say Show us how this does 

 take place. So far from its being unreasonable to put the 

 above question, it would be reasonable to ask not only for 

 ^2^ossible mode of special creation, but for an ascertained 

 mode ; seeing that this is no greater a demand than they 

 make upon their opponents. 



And here we may perceive how much more defensible 

 the new doctrine is than the old one. Even could the sup 

 porters of the Development Hypothesis merely show that 

 the origination of species by the process of modification is 

 conceivable, they would be in a better position than their 

 opponents. But they can do much more than this. They 

 can show that the process of modification has effected, and 

 is effecting, decided changes in all organisms subject to 

 modifying influences. Though, from the impossibility of 

 getting at a sufficiency of facts, they are unable to trace 

 the many phases through which any existing species has 

 passed in arriving at its present form, or to identify the in 

 fluences which caused the successive modifications ; yet, 

 they can show that any existing species animal or vegeta 

 ble when placed under conditions different from its pre 

 vious ones, immediately begins to undergo certain cJianges 

 of structure fitting it for the new conditions. They can 

 show that in successive generations these changes continue, 

 until ultimately the new conditions become the natural 

 ones. They can show that in cultivated plants, in domesti 

 cated animals, and in the several races of men, such altera 

 tions have taken place. They can show that the degrees 

 of difference so produced are often, as in dogs, greater than 

 those on which, distinctions of species are in other cases 

 founded. They can show that it is a matter of dispute 

 whether some of these mqdified forms are varieties or sepa- 



