58 CLAUDE FULLER. 



sioii of their basal region. Pigmentation , which synchro- 

 nises with chitinisation, takes place very slowly and not 

 until after the wings have fully expanded. First the 

 head, then the body and legs, and last the wings become 

 coloured and hardened ; the whole process taking place in 

 complete darkness. The pigmentation of the head and of 

 the sclerites appears to begin at a central point and then to 

 spread outwards; that of the wings begins at the roots, and 

 has the appearance of flowing along the ribs and out from 

 them into their branches, whether such branches were pre- 

 ceded by actual tracheal connections or have arisen from the 

 fusion of thickenings forming about approximated or applied 

 trachea?. For this reason a cross-rib is usually more strongly 

 attached to the more chitinised of the two principals it 

 connects although, ontogenetically, it may be a branch of the 

 weaker. The unfolding and hardening of the wing is a 

 peculiarly slow process. After the last moult, the wings of 

 C. durbanensis unfold in the course of several hours — 

 probably three or four — but nearly a full Aveek elapses before 

 the body is fully chitinised and the wings hardened. Through- 

 out the greater part of this period there is a distinct lumen 

 in the post-costa, sub-costa, radius, media, and cubitus and 

 the main oifsets of these ribs, whilst a lumen representing 

 the anal trachea lies within the anal field, fig. 6S (PI. VI). 

 Except the basal branch of the post-costa], ,*•., fig. 68, there 

 is no such lumen in the marginal nor in the cross-ribs, minor 

 branches, and ridges. The lumen is a capillary air-tube from 

 which the air slowly disappears, often giving the effect of a 

 broken column of mercury in the tube of a thermometer. 

 When the wings are first unfolded traces of the tracheae 

 can be made out here and there, more especially at the bases 

 of the wing, and then the spiral is drawn out, fig. 69. In 

 Termes natalensis and allied forms, the expansion of the 

 wing and the complete hardening of the adult seems to proceed 

 much more slowly, and there is some reason to believe that 

 the better part of a month elapses before the adult insect is 

 perfectly developed. 



