THE EMBRYOLOGY OF THE HONEY BEE 171 



ventral. The anterior and posterior outgrowths of the sacs of 

 the same side meet and fuse with one another to constitute the 

 longitudinal trunk (Fig. 66, TraTr), while the ventral outgrowth 

 (TraCom) of each sac continues to extend ventrad until it meets 

 with the corresponding one of the opposite side. These then 

 fuse to form the transverse commissures (compare Figs. XI and 

 XII). The dorsal outgrowths continue to extend in the same 

 direction, at the same time breaking up into ramifying twigs, and 

 form the dorsal branches (Fig. 66). The anterior outgrowths 



Com~ 



— SpBr 



TraTr 



-.-SpBr. 



Fig. 66. Sagittal section through the rudiments of the tracheal system 

 of one side in trunk segments 2-4, of an embryo Stage X-XI. Developing 

 oenocytes (Oen) also shown, x 387. 



of the first pair of tracheal sacs take a course cephalad and 

 dorsad over the mid-intestine and meet and fuse at the dorsal 

 mid-line to form the anterior tracheal loop. The posterior out- 



