104 THE EMBRYOLOGY OF THE HONEY BEE 



appearance. The head and trunk are sharply separated from 

 one another by a deep constriction. The head has become broader 

 and its sides rounder; the trunk segments are marked off from 

 one another by sharply defined constrictions. The germ band or 

 rather that part of it constituting the body wall of the future 

 larva has increased in width until it now virtually covers the entire 

 yolk, its lateral margins uniting along the dorsal mid-line. At the 

 same time the head has turned ventrad through an angle of about 

 forty-five degrees, so that the labrum, which formerly projected 

 nearly straight out in front, is now directed obliquely ventrad, and 

 the mouth, whose position up to this time corresponded to the 

 cephalic pole of the egg, is now brought to the ventral surface. A 

 similar change occurs at the posterior end of the embryo. The 

 proctodaeal invagination makes its first appearance on the dorsal 

 side of the posterior end of the egg (see Fig. Xa, Pro), the poster- 

 ior end of the germ band since Stage VII having been curved 

 around the caudal pole of the egg, and the embryonic hind-intestine 

 up to this stage has accordingly had an oblique course, being di- 

 rected obliquely caudad and dorsad. Now its direction corresponds 

 with the long axis of the embryo, and the anus having come to lie 

 precisely at the posterior end both of the embryo and of the egg. 

 Since at Stage VIII both ends of the germ band were seen to 

 have been bent around the two poles of the egg, these changes 

 therefore represent a partial straightening of the embryo, and 

 since the whole embryo does not appear to have materially in- 

 creased in length, judging by its relation to the chorion, it must 

 be assumed that the ventral half of the embryo has contracted, at 

 least to a certain extent. 



The labrum has meanwhile changed little in form. The trito- 

 cerebral swellings have completely vanished, the area formerly 

 occupied by them being now smoothly rounded. The antennae 

 are large and somewhat conical in form, and directed cephalad. 

 The mandibles have not perceptibly changed. The first maxillae, 

 however, have lengthened slightly and their peripheral portions are 

 plainly seen to be turned inward. The second maxillae have be- 

 come bluntly conical in form, and slightly flattened dorsoventrally, 

 lying close to the ventral surface of the head, and directed ceph- 

 alad. At the same time their bases have approached the ventral 

 mid-line, carrying with them the openings of the silk glands. 



