704 PROCEEDINGS OF THE NATIONAL MUSEUM. vor .. xxvi. 



I. THE ONTOGENY OF THE VENATION. 

 Historical. 



It is pleasant to find that the first contribution to the knowledge of 

 developing veins was made by Dr. Hagen. In 1846 he published a 

 little paper, a page in length, entitled Ueber die Bildung des Geaders 

 der Libellen-tiiigel," In this he wrote that by simply rubbing the 

 expanding wing of a transforming dragon-fly between the thumb andi 

 finger the two membranes of the wing may be slipped apart, audit 

 will be readily seen that the venation is double, i. e., developed alike; 

 in both membi-anes, and that the double network thus formed is united' 

 and exactly coincident along the courses of the wing trachea. At this 

 day one who wishes to see the relation of veins to trachea3 can hardly 

 do better than repeat this simple experiment. Thus he may at leasts 

 see, a thing too little comprehended hitherto, that the trachea? passing 

 out from the body cavity into the wing cavity are essentially internal 

 organs as compared with the cuticular (hypodermal) thickenings formed 

 about them constituting the veins. 



Oswald Heer appears to have been the first to use the wings of 

 dragon-fly nymphs as an aid to interpreting the homologies of the adult 

 venation.* He made no use of trachea?, however, but only of the 

 veins marked upon the exterior of the wing sheath, these being essen- 

 tially the same a.s the veins in the adult only served to confirm him in 

 an erroneous interpretation of homologies. 



Roster first figured the tracheation of a nymphal wing.^ His figure 

 (of ^Exclina cyanea) was made to show tracheal distribution without 

 reference to venation. It is in several points incorrect, and a chance 

 remark in the text shows that Roster did not perceive the order which I 

 exists in the ai-rangement of the trachea?.'' 



In 1888 Brauer and Redtenbacher published a paper on immature 

 insect wings, using mainly a species of /Eschna to show the fallacy of 

 Adolph's theory of alternating convex and concave veins.*^ Of the* 



"Stettiner Ent. Zeit., VII, pp. 115-116. A similar paper by Dr. Hagen, Kurze > 

 Benierkung ueber das Flugelgeiider der Insecten ( Wien. Ent. Zeit., V, pp. 311-312), 

 was called out in 1886 by the theories with which Adolph and Redtenbacher IukI 

 encumbered their useful works upon the homologies of the wing veins in general. 

 Then in 1889 he published (Spaltung eines Fliigels um das dopplete Adernetz zn 

 zeigen, Zool. Anz., XI, pp. 377-378) a similar article with a figure, shewing the main 

 facts set forth in all these papers. 



''Heer, Oswald, Die Insectenfauna der Tertiargebilde von Oeningen und von 

 Badoboj in Croatien, Neue Denkschr. Schweiz. Ges., XI, 1850, Libellulidw, pp. 

 36-89, pi. IV. 



'Roster, D. A., Contributo all 'anatomia ed allabiologia degli Odonata, Bull. Soc. 

 Ent. Ital., XVII, pp. 256-268, 2 pis. 



'/Mandando in questo percoreo cinque o sei diramazioni che innervano intrecciandosi 

 in rano modo, la superficie dell 'ala. [The italics are mine.— J. G. N.] 



^Ein Beitrag zur Entwickelung des Flugelgeaders der Insecten, Zool. Anz., XI, 

 pp. 443-447. 



