92 EMBRYOLOGY OF INSECTS AND MYRIAPODS 



belonging to the anterior rudiment. Nelson, unwilling to commit him- 

 self as to the germ layer's giving rise to the two rudiments, uses for them 

 the term "mesenteron." From Strindberg's account (1914) it appears 

 that the development of the mid-gut in Vespa vulgaris is similar. 



In the leaf-cutter bee {Trachusa serratulae) Strindberg (1914a) 

 found that the mesenteron rudiments each give rise to a broad ribbon 

 on each side, which grow toward each other until they meet and then 

 broaden, first meeting dorsally and then ventrally. 



As described by Carriere and Biirger (1897) the mesenteron of the 

 mason bee (Chalicodoma muraria) is derived, independent of the meso- 

 derm, from two proliferating areas of blastoderm, one at each end of the 

 germ band, corresponding to the future location of the stomodaeum and 

 proctodaeum, respectively. From each a pair of ribbons arises, as in 

 Trachusa. The mesenteron rudiments here differ from those in the 

 honeybee in that the latter are directly continuous with the ventral 

 plate, whereas in Chalicodoma they are independent, as they are in the 

 bluebottle fly (Calliphora). 



The development of the mid-gut epithelium in ants of the genera Myr- 

 mica, Formica, and Camponotus differs from that of the other aculeates 

 in that it arises as a sheet of cells that forms on the inner surface of the 

 inner layer, designated by Strindberg (1913a) as "definitive entoderm." 

 Anterior and posterior mesenteron rudiments are not present. Tan- 

 quary's account (1913) of the development in Camponotus herculeanus 

 and Myrmica scahrinodis differs in that the epithelium is said to arise 

 on the dorsal side of the yolk augmented by cells from the posterior 

 end of the germ band as well as scattered cells of the inner layer of 

 peripheral protoplasm. 



The literature list given at the end of Chap. VI is applicable to this 

 chapter also. 



