THE EMBRYOLOGY OF THE HONEY BEE in 



which he terms "hypopharyngeal papillae," and which he believes 

 contribute to the formation of the definitive hypopharynx. These, 

 however, are clearly not to be considered as comparable to seg- 

 mental appendages, for obvious reasons. 



The three following segments, the first three of the primary 

 trunk division, the mandibular, and the first and second maxillary 

 segments, are in most respects similar to those of the embryos 

 of other pterygote insects. The appendages (Md, iMx, 2Mx) 

 up to the time of hatching are in the honey bee simple in 

 form, and do not exhibit any differentiation into lobes. Folsom 

 (1900) has discovered in Anurida, a primitive apterygote insect, 

 plain evidences of an additional segment intercalated between 

 the mandibular and first maxillary segment and bearing on its ven- 

 tral surface a pair of papillae, representing a pair of rudimentary 

 appendages (Fig. 36, Slin). These fuse with a median tongue- 

 like evagination of the first maxillary segment (Lin) to form the 

 hypopharynx or lingua of the mature insect. This segment, with 

 its corresponding structures, is wanting in the embryo of the honey 

 bee as is apparently also the case in other pterygote insects. 



The three segments next in order bear the legs (iL, 2L, jL) 

 the rudiments of which appear on the surface, at Stage X, as low 

 protuberances, but are withdrawn from view shortly before 

 hatching. 



The remaining segments, twelve in number, constitute the defin- 

 itive abdomen of the adult in insects other than those of the 

 Hymenoptera. In this order, as is well known, the first abdominal 

 segment is usually united to the third thoracic segment (metatho- 

 rax) and may be said to constitute a part of the definitive thorax. 

 In the embryo of the honey bee, as in those of most of the higher 

 pterygote insects, the abdomen consists of eleven segments plus a 

 terminal or anal segment. Only ten abdominal segments anterior 

 to the terminal segment are usually visible from the exterior 

 (Figs. Xa and XI). Sections cut in the sagittal plane through 

 embryos of Stage XI-XII (Fig. 48A) show that just anterior to 

 the short terminal segment there is a short and much reduced 

 eleventh segment, from which a rudimentary pair of ganglia are 

 produced. The number of segments present in the 'abdomen of 

 the honey bee is therefore the same as that found by Heymons 

 (1895, iSgsa) in the Dermaptera and Orthoptera. 



