THE EMBRYOLOGY OF THE HONEY BEE 7 



membrane has been studied by Tichomiroff (1885) in the silk- 

 worm, more recently by Lecaillon (1897), and by Lecaillon and 

 Henneguy conjointly (1903) in the eggs of the representatives 

 of several orders of insects. These investigators have all found 

 that the chorion is not composed of chitin, as is the integument 

 of the imago, but of a peculiar substance differing in composition 

 from both chitin and horn, which Tichomiroff has termed chorio- 

 nin. The tests employed by these investigators have not been 

 applied to the chorion of the bee's egg, but it is altogether prob- 

 able that it also is composed of chorionin. 



Like other insect eggs the chorion of the bee's egg is not 

 smooth but sculptured. This sculpturing takes the form of deli- 

 cate ridges forming a meshwork over nearly the entire egg 

 (Fig. iA). The meshes have the forms principally of pentagons 

 and hexagons elongated in the direction of the long axis of the 

 egg. Examination under high power shows that the ridges 

 forming the polygons (Fig. iB) are made up of minute circular 

 papillae fused together at their bases, and that similar papillae are 

 scattered about over the area within the polygons. Patterns of 

 this general character are commonly found among insect eggs, 

 the polygons representing merely the imprint of the ovarian folli- 

 cle cells which secreted the chorion. At the posterior end of 

 the egg the ridges fade out and disappear. At the extreme an- 

 terior end the ridges converge toward a small area over which 

 the chorion is conspicuously thickened. This area in general 

 appearance and position corresponds to the micropylar area in 

 other insect eggs and will accordingly be termed such (Fig. 2). 

 It consists of a plate-like thickening of the chorion, approximately 

 circular in outline, whose margins are continuous with the ends 

 of the ridges mentioned above. This thickening exhibits a num- 

 ber of what appear to be perforations or fenestra ; these are very 

 irregular in outline and at the edges of the micropylar area merge 

 with the spaces between the ridges. 



In other insect eggs the micropyle is a perforation or system 

 of perforations of the chorion permitting the entrance of sperma- 

 tozoa into the substance of the egg. Frequently the micropyle is 

 very complex in structure, and sometimes closed by a gelatinous 

 plug. It is very frequently, although not always, situated at the 

 cephalic pole of the egg. The writer has not been able to demon- 



