314 THE CAUSES WHICH 



island; and the short or chill season would eliminate summer 

 forms of the Geometrical Moths from the brushwood. Or^ on 

 the contrary, were the now submerged lands raised, and the 

 circles of distribution wheeled northward, we should meet the 

 orange variety of the Brimstone Butterfly flitting along our lanes, 

 brighter colours would begin to paint our larger-winged moths 

 among the shady lanes and on the moorland, and generally species 

 would appear in a greater number of annual broods, and exotic 

 species commence to take possession of the land. 



Now, if we take into account the change of surrounding soils 

 and vegetation to which the foreigners would be exposed, it is 

 evident the little-understood Providence of protection by mimicry 

 would be disturbed, and the introduced species must vary in 

 harmony or sviffer decimation ; or should the change in the sub- 

 ordinate and sustaining floral realm be regarded, larger or smaller 

 species would be produced, or colours, and probably secretions, 

 generally change. It is thus the selection of species will gain in 

 Importance when viewed with regard to its application to unravel 

 enigmas that present themselves in the palseontology or history 

 of the European flora and fauna. And when we consider the 

 operation of these vicissitudes in soil, vegetation, and climate, 

 the incessant struggle for existence or domination, the migrations 

 and adaptations to which organic life must have been subjected 

 by the incessant interchange of sea and land during the formation 

 of the super-granitic crust of our globe, we are thus led to the 

 conception of existing kinds being climatic or protected forms of 

 others pre-existing, or in other words, the functions of a variable 

 environment and the exponents of atavism. Regarded in this 

 light, our present life is no more to be considered new, but as 

 having come to us rather the product of a world-old manufactory^ 

 that has stamped with its die on plastic shapes many a curious 

 scutcheon and by-gone crest of glory, wherein the learned decipher 

 mechanically but genera and species, and where the schoolboy 

 sees but delight. 



Neither are these views brain-spun, nor do we at all tread the 

 threshold of a vision. Fluctuations quite unhjrpothetical continue 

 in our day to be manifested by the changing seasons, and these 

 engrave the record of their visitations on the life in districts and 

 localities. English summers come to us unprecedentedly wet 



