JOURNAL 



J}f\B ]9opfe 6lntoinoIogirHl Horiptg. 



\^ol. VIII. MARCH, 1900. No. 1. 



THE DEVELOPMENT OF THE WINGS IN THE 

 LEPIDOPTERA. 



plates i-v. 



By William Fairfield Mercer. 



The development of the wings inside of the body of the larvae of 

 insects with a complete metamorphosis is one of the most striking 

 features in the transformations of insects ; it is, however, one that is 

 not generally understood. Although the fact that caterpillars have 

 wings was discovered by Malpighi (1687) and by Swammerdam 

 (173*^)5 it is only in the last half of the present century that any 

 exact information as to their method of development has been ob- 

 tained ; and this information is only just finding its way into the 

 general text-books. 



The beginning of the solution of the problem was made by 

 Weissmann('64 and '66) in his remarkable papers on the development 

 of flies. These papers were followed by important contributions by 

 Landois ('71), Ganin ('76), Dewitz ('81), Pancritius ('84), Schaffer 

 ('89), Mayer ('96), Gonin ('92), and others. The most complete 

 account that has yet appeared is that of Gonin. 



Nearly two years ago, in the course of some studies of the develop- 

 ment of the wings of Pieris, Professor Comstock came to the conclu- 

 sion that in some respects the excellent account by Gonin was inac- 

 curate. And at his suggestion I undertook the repetition of the 

 tracing of the development of the wings in this insect. The follow- 

 ing paper is the result of this investigation. 



As Gonin's contribution appeared in a journal which is to be found 

 in but few libraries in this country, it seems worth while to publish for 

 American readers my complete results even though in many particu- 

 lars they duplicate the results of Gonin. 



