THE GENESIS OF THE TERMINOLOGY 5 



knowledge and did much to retard the progress of the solution of the 

 problem of which it treated. 



In this work Adolph elaborated a theory of alternating convex and 

 concave veins. This was based on the fact, already pointed out by several 

 writers, Selys-Longchamps, Saussure, Hagen, and others, that as a result 

 of a corrugation of the wings some of the veins extend along raised lines and 

 others along stniken ones. He also made use of the results of Landois 

 concerning the relation of the trachese of the wings to the wing-veins. 



According to this theory the wing trachea; determine the position of the 

 concave veins, which represent the foundation of the vein system. Only 

 later is each tracheal tube inclosed by a mass of chitine and thereby trans- 

 formed into a vein. At the same time, according to Adolph, the tracheae 

 force the two wing-plates apart and cause a thinning of the membrane, 

 which shows itself, among other ways, by the fact that the wing regularly 

 tears under pressure or strain along the concave veins. Between these 

 primary, or concave veins appear later thickenings of the wing-membrane 

 in the form of chitine lines with which the tracheal tubes and blood channels 

 are finally associated, and which form the secondary, or convex veins. The 

 two sorts of veins, accordingly, stand in direct opposition to each other; 

 since the first is produced by a thinning, and the last by a thickening of the 

 wing-membrane; and since, in the former, the tracheal tube, in the latter, 

 the chitinous lines represent the primary foundation. 



Subsequent investigations have shown that there is little to support 

 this remarkable theory. There is only one method of formation of the 

 principal wing-veins; and the differences in position of the veins, that is 

 along raised lines or along sunken ones, is merely the result of a secondary 

 coiTugating of the wings. 



Redtenbacher was profoundly influenced by the theory of alternating 

 convex and concave veins elaborated by Adolph and made his system of 

 terminology conform to it absolutely. He recognized five fields in the 

 wing each traversed by a convex vein. These veins he designated by the 

 consecutive odd Roman characters: I, HI, V, VH, and IX. He also 

 applied to these veins the names costa, radius, media, ctibitus, and anal 

 vein. 



These names he selected from the many names then in use except in the 

 case of media, which was proposed by him for the vein to which that name 

 is now applied; and which previously had been generally regarded as 

 belonging partly to the radius and partly to the cubitus; although it had 

 been recognized as a principal vein by Edward Doubleday long before. 

 See his "Remarks on the Genus Argynnis" (Trans. Linn. Soc. vol. XIX, 



1845)- 



To the concave veins, which Redtenbacher, following Adolph, believed 

 to alternate with the convex veins, be applied the consecutive even Roman 



