The origin and development of the wings of Coleoptera. 55S 



easily malformed and in no way fitted for its work as an organ of 

 flight. Soon after pupation each hypodermal cell develops a dense 

 bundle of fibres which are attached to the cuticula by a cone shaped 

 base and are continued down through the length of the cell to the 

 basement membrane, where they are firmly united to corresponding 

 fibres from the other side of the wing (PI. 18, Fig. 50 h'drm. rd). 

 These fibres develop also in the prolongations of the basal ends of 

 the hypodermal cells in the basement membrane. The whole wing is 

 thus bound together from side to side and end to end by a complex 

 system of these strong connectives. These rods, or fibres, are easily 

 demonstrated after killing with subHmate acetic acid, Flemming or 

 Hermann's, but not after Perenyi, hot water, or any Picric acid mixture. 

 Alum Carmine and Picric acid, or Heidenhain's Iron Haematoxylin 

 furnish excellent images of these structures. 



While this development of the connecting fibres in the elytron is 

 going on the basement membranes separate and between them the 

 cavities of the veins become continuous forming a large middle space, 

 which is simply the cavity of the wing formed by the first evagination 

 reopened, and is in no sense a secondary internal cavity. This middle 

 space is not, however, in communication with the subhypodermal spaces 

 (PI, 18, Fig. 51 s'h'drm.sp), being separated from them by the 

 basement membrane, which, however, is frequently fenestrated. Often, 

 as pupation goes on, the middle space becomes greatly distended with 

 haemolymph which rarely enters the subhypodermal spaces. 



In the Lepidoptera, Mayer (1896) has described canals passing 

 across the middle space of the wing and putting the two subhypo- 

 dermal spaces in connection with each other. In the Coleoptera 

 similar structures are found where some half dozen hypodermal cells 

 become grouped in a ring (PI. 18, Fig. 49) and have the "grund- 

 membranes" connected, forming a tube between the two subhypodermal 

 spaces. These groups of cells are in some species arranged in definite 

 rows (L. decemlineata) and irregularly in others (0. scabra). During 

 the pupal stage these structures show no further change, but in the 

 adult they are the places where the chitinous columns of the elytra 

 are developed; in the hind wings they remain in this condition 

 throughout life, as they do in the Lepidoptera. 



In the pupal stage each wing is surrounded by a chitinous sac 

 as in the Lepidoptera (Mayer 1896), and at first the surface of the 

 wing and this sac are parallel and in contact, but the wings soon 

 become folded. The wings are also much distended with haemolymph 



