PART V. THE COLLECTION AND PRESERVA- 

 TION OF INSECTS. 



BY W. J. HOLLAND, PH.D. 



CHAPTER XL. 

 THE CLASSIFICATION OF INSECTS. 



IT is estimated that four-fifths of the species comprised within 

 the animal kingdom belong to the class of the Insecta. Fully 

 one hundred and seventy-five thousand species of insects have 

 already been named and described. Nevertheless vast terri- 

 tories teeming 1 with insect life have been as yet only very iin- 

 perfectly explored. The life-history and habits of only a few 

 thousands of species have as yet been accurately investigated. 

 There remains, therefore, a broad field for discovery and re- 

 search in this portion of the animal creation. 



Many insects are potygoneutic, that is, the species is repre- 

 sented by two or more annual broods, or generations, and thou- 

 sands of individuals may, by careful treatment, be reared from 

 the eggs of a single female. In the case of the higher animals 

 the development and multiplication of individuals takes place 

 but slowly, and it is obvious, therefore, that there is in the do- 

 main of insect life a far more convenient field for the investi- 

 gation of the great problems of variation in animal forms, than 

 among the vertebrate animals. Aberrant forms are not uncom- 

 mon, especially among butterflies and moths, and arc worthy of 

 careful study. The various broods often present great and 

 striking differences. The phenomena of seasonal and sexual 

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