86 Permanence and Evolution. 



the two " lines of stock " kept by Tomkins, the 

 original breeder, distinguishable by colour chiefly, 

 and, as usual, of the ultimate origin of those sub- 

 types nothing is known. 



It is said that Darwinism undertakes to prove, 

 first, that species can possibly be formed by 

 natural selection ; secondly, that if they are so 

 formed, it accounts for a great deal of what we 

 see. It is evidently primarily necessary to prove 

 the first, and we see that nothing can be shown 

 for it except vague hypotheses and supposed 

 probabilities, not unlike some to be found in 

 systems of continental jurisprudence. If in any 

 other branch of science facts are stated, they are 

 understood to have been proved. If, for instance, 

 in chemistry we are told that water is produced 

 from oxygen and hydrogen, we understand that 

 the experiment has been tried by scientific men 

 of known repute, under conditions carefully 

 selected to avoid the possibility of mistake, and 

 continually verified afterwards ; so if we hear 



