Dec., '07] ENTOMOLOGICAL NEWS. 427 



as regards superficial modification and adaptation, these kinds 

 occurring in closely massed great series of individuals, easily 

 observed in nature, readily obtainable as laboratory and mu- 

 seum material, conveniently and economically reared and ex- 

 perimented with, well known systematically and morphologi- 

 cally, and so abundant, widespread and adaptive that they have 

 carried to an extreme almost all types of ecologic shifts for a 

 living. They truly offer themselves as the most accessible of all 

 animal material that the student of evolution problems can 

 work with, and yet they compose that animal group relatively, 

 if not absolutely, least taken advantage of for this purpose. 



The number of known insect kinds is, roughly, about 350,- 

 ooo ; more by far than the total of all kinds in all the other ani- 

 mal classes taken together. This very weight of existent spe- 

 cies, coupled as it is with an equally extraordinary high nu- 

 merical representation of individuals brings about a life pres- 

 sure which has resulted in the high development of a great 

 variety of adaptation; adaptation in food-getting, in means of 

 defense and offense, in egg-laying and care of young, in nest- 

 building, in a score of other phases of specialized life. This 

 adaptation or modification, both structural and functional, in 

 its turn leads swiftly and variously to species-change that is, 

 to species-forming. And adaptation and species-forming are 

 the two fundamental and co-equal problems of evolution to- 

 day. 



But there are various outworks of the grand problems to be 

 attacked, one or a few at a time. There are various avenues or 

 lines of approach to the problems. Such lines or phases of the 

 general study of evolution are denoted under the various titles 

 of variation, heredity, isolation and distribution, parasitism, 

 commensalism and symbiosis, color and pattern, regulation and 

 regeneration, and others. 



It is my wish to refer simply, and almost in cataloging man- 

 ner, in the few minutes at my disposal, to some of the contribu- 

 tions already made from insect biology to the study of these 

 evolution problems, and to point out further work and oppor- 

 tunity that lies ready to our hands. 



In variation studies the opportunity afforded by the insects 



