364 THE CANADIAN NATURALIST. [Vol. viii. 



therefore, to the same family as the locusts of Scripture, those 

 people are greatly at sea who imagine it be specifically identical 

 with any of the Asiatic or European species. It is known to 

 entomologists as Caloptenus spretus, and is purely American, 

 since it does not inhabit any other continent. 



Evolutionists believe — and I am one of them — that existing 

 species are but the modified descendants of pre-existing species. 

 The present species of a genus have at sometime, more or less 

 remote, had a common ancestry. All life exhibits a certain 

 power of adaptation to surrounding conditions, and through what 

 is known as " natural selection " (two words which by Darwin's 

 pregnant pen have come to express volumes of facts and conse- 

 quences), coupled with other less easily formularized laws, the 

 fauna and flora of the globe have been as profoundly changed as 

 have its physical conditions. The influences that have thus 

 worked in the past are still working at present — less rapidly, per- 

 haps, in the main, but none the less effectually. Among higher 

 and more complex animals the changes are slow and not very 

 noticeable; the species have become, in most cases, markedly dif- 

 ferentiated, aud their characters are well fixed. Among lower 

 organisms these changes are more obvious, and naturalists are 

 sorely puzzled in their endeavours to grasp and express them. 

 This is especially the case among insects. We have the simple 

 variation from the typical characters of a species ; we have phy- 

 tophagic varieties, or those departures from the type that result 

 from the kind of food assimilated during growth ; we have phy- 

 tophagic species, or those variations which have become fixed and 

 permanent in the adolescent or immature stages through some 

 peculiar and fixed habit, without having yet modified the imago 

 or mature state; we have geographical variation, increasing — 

 usually with distance — until the separation from the type is suf- 

 ficient to be indicated by what we call race; we have seasonal 

 variation, sexual variation, and, finally, we have the terms dimor- 

 phism, beteromorphism, and many other isms, to express still 

 other variations. In short, in the strain, the breed, the sport, the 

 tribe (in the popular sense), the variety, and the race, we have 

 so many terms invented to indicate some of the more patent 

 steps in the evolution of one species from another, and between 

 them all there are so many shades of variation for which no words 

 have yet been coined, that the naturalist who takes a comprehen- 

 sive view of life upon our planet finds that what we have chosen 



