THE GENESIS OF THE TERMINOLOGY 9 



in order to better adapt their parts to perform their functions. By the old method a 

 search is made for characters by which a group can be divided and subdivided with but 

 little regard to the meaning of these characters. In fact we rarely see in purely taxono- 

 mic works any reference to the functional significance of the characters used. 



"As illustrating the proposed method of study, the structure and function of the 

 wings of the Lepidoptera are discussed and conclusions arc drawn from this study 

 regarding the phylogenetic development of the order." 



The next step in advance in the development of the nniform nomen- 

 clature of the wing-veins was made by the writer, who worked out the 

 homologies of the wing-veins of the Lepidoptera, Diptera, and Hymehop- 

 tera and published his results in "A Manual for the Study of Insects" 

 (1895). In the preface of the book he said: 



"The principal features of notation of wing- veins proposed by Josef Redtenbacher 

 have been adopted. But as the writer's views regarding the structure of the wings 

 of primitive insects are very different from those of Redtenbacher, the nomenclature 

 proposed in this book is to a great extent original. The chief point of difference arises 

 from the belief by the present writer that veins IV and VI do not exist in the Lepidoptera, 

 Diptera, and Hymenoptera; and that, in those orders where they do exist, they are 

 secondary developments." 



I had already reached the conclusion that the few-veined wings of 

 Hepialus represented the primitive type more closely than the fan-like 

 wing of the Ephemerida, as was commonly believed. But as I had not 

 made, at that time, careful studies of the wings of insects with many wing- 

 veins I was willing to admit that the veins IV and VI of the Redtenbacher 

 system might exist as secondary developments in those orders with fan-like 

 wings. 



The investigations of the writer referred to above were based on 

 examinations of the wings of adult insects. Soon after the publication of 

 the volume just cited, Mr. J. G. Needham, then a graduate student in the 

 entomological laboratory of Cornell University, and the writer began the 

 investigation of the development of the wings of representatives of all of 

 the orders of insects of which we could obtain living n^nnphs or pupae. 

 The results of these ontogenetic studies were published in a series of articles 

 entitled "The Wings of Insects," which appeared in the American Naturalist 

 during the years 1898 and 1899. This series of articles established on a 

 firm basis the uniform terminology of the wing-veins. The results of our 

 investigations are given in detail in subsequent chapters. 



In recording the results of our studies we found it necessary to introduce 

 an important modification of the Redtenbacher system. As the non 

 existence of veins IV and VI of the Redtenbacher system was demon- 

 strated, and as it was desirable that the numbering of the principal veins 

 should be continuous, a modification of the Redtenbacher system was 

 obviously desirable. But we were met by another difficulty due to the fact 

 that Spulcr and others did not regard the costa as a vein and began their 



