THE CANADIAN ENTOMOLOGIST. 129 



issues from the egg early in August in average seasons, and its term of 

 hibernation, beginning soon after the middle of August, continues until 

 approximately the beginning of May, so that ordinarily hibernation lasts 

 somewhat more than eight months. Emerging from its winter shelter 

 early in May, the juvenile larva re-enters active life, still a literal infant 

 though over eight months old*. 



So chilly are the May nights, and many of its days also, that more 

 than half this active period of the larva must be passed in a state scarcely 

 different from actual hybernation. The conditions of life are doubtless 

 somewhat restrictive, and a removal of these disabilities, by rearing the 

 caterpillars in a warm house, is like an introduction into the tropics. 



The result of this culture in an improved climate, other circumstances 

 being favorable, is a notable progress of type, an outcome of butterflies 

 definitely in advance of the ordinary averages. 



One of the bred families illustrates well this immediate improvement 

 of type. This lot comprises nine ^ s and ten Js, and is a natural family 

 from eggs of one ?. The increased size of these specimens, as compared 

 with the caught lot, is decisive. The twenty-nine caught ^ s average 

 51 1-5 mm.; the nine ^s of this family show an average expanse of 53^ 

 mm. Only one of the ^ s of this family expands less than the average of 

 the caught ^ s, each of the remaining eight exceeding that average. The 

 ten $s average 57^ mm., against 521.^ mm., as the average measure 

 of the 62 caught $ s; indeed, each of the ten ^ s of this brood is decidedly 

 beyond the average of the caught ^ s, none being under 55^ mm. One 

 of the $ s, measuring sixty mm., is slightly over 2.36 inches, is the largest 

 E/is in my series. These nineteen specimens are as much superior to 

 the caught material, in average of pattern elaboration, as in size. At a 

 first general view they might almost suggest the idea of a distinct species, 

 so superior are they as a body to the general mass of the caught set. 

 But the difference would become intelligible to any careful observer, on 

 inspection, as a simple advance of one set beyond the average development 

 of the other ; a difference in degree, not a change in method. This dis- 

 tinction between quantitative and qualitative differences is the vital point in 



* I hope none of my younger readers entertain the absurd medireval superstition that 

 hibernating caterpillars pass the winter in a frozen condition. In successful hibernation 

 they do not get near to such a condition ; but if they do absolutely freeze, then are they 

 undone caterpillars. Valkyria gives them sleep, unmi.xed with dreams, and they wake in 

 Valhalla. 



