as involving an absurdity (which I believe to be the 

 exact opposite of the truth), I would, in the present 

 state of our knowledge, desire rather to regard it as a 

 postulate, assumed to illustrate the doctrine of species, 

 than as a problem capable of satisfactory demonstration. 

 The second of the above definitions may likewise 

 require briefly commenting upon ; for I have frequently 

 heard it asserted that everything is to be regarded as a 

 ' ' variety ' which has wandered in the smallest degree 

 from its normal state. Now this I contend is essentially 

 an error ; for a ' ' variety," to be technically such, must 

 have in it the primd-facie elements of stability, and to 

 an extent moreover that, without the intermediate links 

 (which, although rarer than the variety itself, must 

 nevertheless exist] to connect it with its parent stock, 

 its condition is such that it might be registered as speci- 

 fically distinct therefrom. Thus, to take an example for 

 illustration, there are many darkly coloured insects 

 which, as every entomologist knows, vary, by slow and 

 regular gradations, into a pallid hue, sometimes into 

 almost white. It also most frequently happens, in such 

 instances, that the extreme aberration is of more common 

 occurrence than the intermediate ones. Here then is a 

 case in point : there is but a single variety involved, 

 namely a pale one, the gradually progressive shades 

 which imperceptibly affiliate it with its type not being 

 regarded in themselves as " varieties ' at all. If this 

 indeed were not so, then would our position be far from 

 pleasant, since we should be compelled to record, as a 



