THE WINGS OF INSECTS. 
J. H. COMSTOCK anD J. G. NEEDHAM. 
CHAPTER I, 
An Introduction to the Study of the Homologies of the Wing- 
; Veins. 
It is the purpose of this series of papers to present a sum- 
mary of what is known regarding the structure and development 
of the wings of insects, to give the results of some investigations 
in these fields made by the writers, and to indicate the value in 
taxonomic work of the characters presented by the wings. 
As the growth of our knowledge naturally proceeds from a 
study of the obvious facts of nature to those that are more 
deeply hidden, it seems best to discuss first the structure of 
the wings of adult insects and to postpone for a time the study 
of the beginnings of wings. It will be necessary, however, to 
take up early in the discussion a study of the structure of the 
wings in those stages that immediately precede the adult stage, 
the -pupz of insects with a complete metamorphosis, and the 
nymphs of insects with an incomplete metamorphosis. It is 
in this field that we have the most to offer that is new. 
Several writers have appreciated the fact that much light 
can be thrown on the problem of determining the homologies 
of the wing-veins by a study of the trachez that precede them 
in the wings of immature insects. The more important of the 
contributions that have been made to this phase of the question 
are those of Brauer and Redtenbacher! and of Spuler.? Still, 
comparatively little has been done in this direction. 
This is doubtless due to the difficulties that have stood in 
the way of work of this kind. The trachez of the wings of 
pupæ and nymphs are often very delicate, and when filled with 
1 Brauer und Redtenbacher, Ein Beitrag zur Entwickelung des Fliigelgeaders 
der Insecten. Zool. Anz., 1888, pp. 443-447. 
2 A. Spuler, Zur Phylogenie und Ontogenie des Fliigelgeiders der Schmetter- 
linge. Zeit. f. wiss. Zool., Bd. liii, 1892, pp. 597-646. 
