128 COLIN CLOUT'S CALENDAR. 



natural selection has fixed steadily upon certain very 

 distinctive or highly important features, and has exag- 

 gerated those to an extreme degree : and then the inter- 

 mediate forms soon die out, because crossing becomes 

 impracticable, and the central stock has ceased to exist. 

 In other cases species merge imperceptibly into one 

 another : so that all one can do is to accept certain ap- 

 proximate types as standards of reference, and consider 

 the intermediate forms as neutral specimens ; because 

 the central form still holds its own, and the various 

 lateral types, slightly favored by natural selection in 

 different directions, still remain capable of crossing with 

 one another at least on their respective borders. To 

 this latter class such plants as the roses and the brambles 

 belong as, indeed, do by far the larger number of our 

 native wild flowers. Indefinite variability and indeter- 

 minate boundaries are indeed the rule ; definiteness and 

 distinctness of limitation are but rare exceptions. The 

 primrose fades away into the oxlip. and the oxlip into 

 the cowslip : till at last even the bucolic inquirer is 

 forced to take refuge in the fundamental doctrine of 

 Hegelianism, and admit that after all in nature every A 

 is also a not-A. 



