174 THE EMBRYOLOGY OF THE HONEY BEE 



2Mx 



TraB 



Fig. 68. Anterior end of a sagittal section laterad of the median plane, 

 from an embryo of Stage XI-XII, showing the development of the deriva- 

 tives of the tracheal invaginations of the second maxillary segment. 

 Hypodermis and brain represented in outline only. Drawn from two 

 sections, x 243. 



of the two branches previously described (p. 168), supplying the 

 brain and first maxillae, the other forms the smaller branch 

 supplying the dorsal part of the head (Fig. 64). 



Hatschek (1877) described what he thought were tracheal 

 invaginations on the gnathal segments of embryos of Bombyx, but 

 examinations of Hatschek's plates show that these invaginations 

 are merely those of the tentorium and mandibular apodemes, and 

 this is the interpretation of subsequent embryologists. With this 

 exception there is no record in the literature of the insect embry- 

 ology of tracheal rudiments existing in the gnathal region. It 

 may therefore be inferred either that this phenomenon is peculiar 

 to the honey bee, or else that it is of more or less general occur- 

 rence, but up to the present time has been overlooked. Of these 

 two inferences the latter seems the more probable. If it were not 

 so, it would be difficult to understand why the honey bee, a 

 specialized member of a group generally regarded as highly 



