rilE TRACHEATION OF WINGS 



41 



of this form because of its large size. The highly specialized bee has 

 specialized tracheal conditions but a study of the figure will recall the 

 conditions in the more generalized insects. The Y-shape of the leg tracheae 

 is as striking in the metathorax of the honey-bee as in the diagram of the 

 typical condition (Fig. 32). In the mesothorax the anterior stem to the leg 

 (as) is greatly elongated and extends dorsally to its connection with the 

 costo-radial {c-r) branch to the wing and then passes ventrally into the leg. 

 The posterior stem (ps.) to the mesothoracic leg {I.2) is united with the 

 anterior stem (as) to the metathoracic leg a short distance from the spira- 

 cular trunk. The spiractilar trunk leading to the vestige of the meta- 

 thoracic spiracle (v. sp-i) is very 

 long. 



The tracheae leading to the 

 muscles of the coxae {mi) are well 

 developed, and as shown in the 

 figure, are united much like the 

 leg tracheae with which they 

 actually connect. But these 

 muscle tracheae lie deeyj within 

 the thorax and are relatively 

 much smaller than the true leg 

 trachese. 



The branches to the wings 

 exhibit the greatest specialization. 

 In the case of both wings the air 

 supply comes entirely from the 

 spiracle anterior to the wing, 

 for there is no connection with the spiracle posterior to the wing. A 

 short distance distad from the union of the two branches to the front 

 wing there will be noticed a slight projection from the tracheae. This 

 projection is in such a position that it is highly suggestive of a vestige of the 

 former cubito-anal trachea which extended from this point to the base of 

 the metathoracic spiracular trunk. In a similar position on the trachea 

 leading to the hind wing there are a few tracheal branches which may have 

 a significance similar to that which has been ascribed to the projection on 

 the trachea leading to the front wing. If these structures represent the 

 vestiges of the cubito-anal tracheae leading to the spiracular trunks, the part 

 of the tracheae between these structures and the union of the tracheae (m) 

 must represent the transverse basal trachea and the remainder of the 

 posterior branch must represent the distal part of the cubito-anal trachea 

 (cu-a). 



Fig. 32. — The basal connections of the tracheae 

 of the wings of Apis. Side view. 



