THE EFFECT OF COLD ON DEVELOPMENT. 1383 



EXCURSUS LIIL— EFFECT OF COLD ON DEVELOPMENT. 



If the butterfly courted the bee, 



And thp owl, the porcupine; 

 If cluinlics were built in tlio sea, 



And llirpc linirs iinc was nine; 

 If Ilie pony loilc his master. 



If the hiiltercuns ato the cows, 

 If the cat had the n'rc disaster 



To be worried, sir, by tlie mouse; 

 If nianiuia, sir, solil the baby 



To a gipsy for lialf-a-crown; 

 If a gentleman, sir, was a lady, 



Tlie world would be Upside-Down. 

 If any, or all of these wonders 



Should ever come about, 

 I should not cciHsidcr them blunders, 



For I should be Insidc-()nt. 



Tdiisy Turvy World 



One has but to compare the variety of" butterflies found in the tropics with 

 that found in the temperate zones to measure the effect of winter upon 

 btitterfly life in general ; for though the dry season of the tropics in part 

 offsets the winter of the cooler regions, there is then no such pervasive 

 suspension of vitalities. So far as butterflies are concerned, the number 

 is comparatively few of those whose sustenance is drawn from plants which 

 are dormant in the dry season and wither to the ground ; and heat and 

 dryness are in themselves no bar to the growth or enjoyment of the 

 former. The same cannot be said of the cold ; not only does it practically 

 destroy the means of sustenance, but it itself condemns to inactivity; and 

 without activity is no growth. 



The lives of butterflies in temj)erate climes is therefore far different, and, 

 relatively speaking, probably far more varied than in the tropics. The cold 

 winter when all activities cease is met by some at one stage, by others at 

 another, by not a few in more than one stage. Rarely does any special 

 provision seem to be made to meet it ; it is as if winter had come upon a 

 given species when members of all stages were astir (as often happens 

 now in semi-temperate regions) and only such stage or stages as are best 

 fitted withstand the shock, until a particular hibernating stage becomes 

 fixed in its history. 



The most noticeable and general effect of cold upon the development of 

 butterflies is seen in the number of annual generations or cycles in different 

 latitudes, whether a single species is considered or the whole body of but- 

 terflies. Thus Brunbauer states, as the result of his comparisons of the 

 life histories of the components of the European butterfly fauna, that north 

 of the Alps one or two generations are the ride, south of the Alps three or 

 more, never, he thinks, exceeding five ; while if we except the few species 

 of this country which everywhere show only a single generation — mostly 

 confined to boreal and alpine types — the [lages of the present work show 

 hardlv an exception to the rule that butterflies which in New England have 



