THE NEW ENTOMOLOGY. Ill 



faction at any rate, the occurrence of mountain and lowland 

 forms. We have our theories of waves of migration, of older 

 and newer arrivals. When we discover Dytiscus lapponicus in a 

 highland loch, Q.nd PacJmobia hyperborca on a highland mountain, 

 we are not simply content with those facts, we must enquire 

 more curiously ; we appeal to the Geologist to interpret our phe- 

 nomena, and the Geologist — on the strictest lines of inductive 

 reasoning— tells us of long past ages of ice, when glaciers slid 

 down the sides of our highland mountain and scooped out the 

 bed of our highland tarn : the PaliBontologist takes up the tale, 

 and speaks of fauna and flora specialized to such Arctic con- 

 ditions. Thus we get hold of the idea of vast secular changes 

 of climate, and of plants and insects gradually changing with 

 changing conditions of temperature and environment ; of our 

 Alpine forms being, as it were, the stranded relics of an older 

 world ; and Entomology takes its place among the other sciences 

 to tell us of the ever- changing procession of life which has been 

 marching across this planet since vitality first began upon its 

 surface. 



Another development of modern Entomology, although this 

 is to a great extent the work of the future, is some investigation 

 into that difficult problem of the irregular abundance and scarcity 

 of many forms of insect life. That there are factors at work all 

 through Nature of which we know little or nothing, influences 

 which guide the ebb and flow of being, we are perhaps only now 

 beginning to learn. To me this field appears to be one of the 

 most interesting and one of the most fruitful that can engage the 

 attention of the modern entomologist, but I foresee that it must 

 be approached by the most strictly scientific methods. I believe 

 that there are subtle correlations and delicate adjustments be- 

 tween various forms, and between form and environment, that 

 elude our most patient research ; and perhaps I may be allowed 

 in this connection to depart for a moment from my retrospective 

 attitude, and to impress upon my readers the incalculable value, 

 in this matter, of careful systematic records kept by a competent 

 body of observers during a long period of time. T venture to 

 believe that this subject has an economic bearing and importance 

 little suspected, while its true solution would throw light on some 

 of the most mysterious phenomena of Biology. 



That, however, is one of the tasks of the future, and I am 

 now discussing more the present position of Entomology. Let 

 us, then, consider for a moment one comparatively modern de- 

 partment of the study from a biological point of view. I have 

 already alluded to the support which many post-Darwinian evo- 

 lutionists have been able to derive from a study of the order 

 Insecta. I need only mention mimicry, as it is called, to instance 

 one case. We all know what is meant by mimicry, and how its 



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