OF ARTS AND SCIENCES. 249 



good an example as any other for an indiflferently colored female of a 

 beautifully colored male. 



But unfortunately it happens that all the females of Pupilio turnus 

 in the northern half of North America are so presumptuous as to 

 show the same gay colors as the male, and even brighter and more 

 variegated ones. Both sexes have as caterpillars the same food in the 

 South and in the North. The chrysalis of the dark and gay-colored 

 females is not different, except that I find in two of the dark ones 

 raised by J. Boll in Texas (there occur both forms) a longitudinal 

 blackish ventral baud which is not to be seen in the chrysalis of the 

 gay-colored females. There is, therefore, no reason left to understand 

 why this species should form such a strong exception. If the males 

 need something besides beauty in their competition for the females, it 

 seems as if the strongest would always be the winner. But is it sure 

 that the most prominent external beauty always coincides with the 

 most prominent sexual power ? I confess that I have some doubt 

 about the fact, as the artificial loss of this power by castration is 

 followed in birds, in mammals, and in an isolated instance in fishes, by 

 an unusual development of external beauty. 



TTie Change of Color. 



The color of insects, or at least its changes, may be originated by 

 the influence of the air and its humidity, of the temperature, of the 

 season in which they appear, of the character of the country. 



The facts to elucidate such important and interesting changes are 

 still scarce and isolated. The curious season dimorphism belongs 

 here. The facts stated in the publications of Weismaun and W. H. 

 Edwards are known to every student, and need not be repeated here. 



The darkening influence of a climate or country with a large 

 amount of average humidity, which is so well proved for vertebrates 

 by Mr. J. A. Allen, has a similar effect on insects. The peculiar col- 

 oration of animals living in deserts is well known, and to a certain 

 degree repeated among insects. The brilliancy of colors in the 

 tropics has become long ago a commonplace remark. Surely there 

 are to be found in the tropics the most brilliantly and intensely col- 

 ored animals, but it must not be forgotten that by far the largest 

 number of insects in the tropics are just as indifferently and as darkly 

 colored as those in colder regions. 



It is a remarkable fact that cold or arctic regions, where snow and 



