80 PARTHENOGENESIS 



membranes : an inner one, the so-called vitelline membrane, and 

 an outer one, the egg-shell or the chorion. Both membranes 

 are extremely thin and delicate : even the outer one, which other- 

 wise (especially in those eggs which are deposited freely) is of 

 considerable thickness and firmness ; the vitelline membrane is 

 structureless, whilst the chorion is covered with a delicate hexa- 

 gonal lattice- work, as with a network, as far as the hinder (lower) 

 flattened end of the egg which serves for its attachment. The 

 micropylar apparatus lies at the anterior or superior pole of the 

 egg, which is the last excluded during oviposition (and after- 

 wards contains the head of the young larva). At this point, 

 where the ridges of the chorionic network run together, we see 

 a little fan-shaped figure (of about y 1 ^ millim.) with about twelve 

 rays. The rays of which the face is composed form the optical 

 expression for the same number of micropylar canals, which run 

 under the surface of the chorion. At their lower diverging ends 

 these canals are open externally, whilst they open into the in- 

 ternal space of the eggs with their opposite extremities. The 

 structure is exactly the same as in a number of other Hymeno- 

 ptera (see M tiller's Archiv, 1855, p. 236. taf. 11. figs. 12, 13), 

 but with this distinction, that in this case the micropylar canals 

 are most extraordinarily thin and delicate ; so that we can hardly 

 convince ourselves with certainty of their real nature, and at the 

 first glance might almost be inclined to regard the rays as ridges, 

 such as also occur on the other parts of the chorion. The canals 

 can hardly be more than j qV o m il nm - m diameter, certainly still 

 sufficient to allow the passage of a seminal filament. During 

 the last period of its stay in the ovary, the Bee's egg receives 

 another external coating of an albuminous nature, which indeed 

 is reduced to almost nothing on the anterior (superior) half, but 

 gradually thickens posteriorly, and acquires a very considerable 

 development at the flattened posterior (inferior) pole. This 

 albuminous deposit serves for the attachment of the egg to the 

 wall of the cell/' Although I do not quite agree with this 

 Leuckartian conception of the micropylar apparatus of the Bee's 

 eggs, and I am especially compelled to regard the above-mentioned 

 micropylar canals as something else, a detailed criticism of this 

 representation of Leuckart's would lead me too far, and 1 there- 

 fore reserve this for another occasion, and will make use of the 



