712 Laura Florence 



so that a fork is formed, between the prongs of which are transverse 

 ridges (Plate LXVI, 28). These structures have no very regular character, 

 and Gross could not determine whether they originated as separate rings 

 or as lamellae. In the vicinity of the furrow between the egg and the 

 operculum the appearance is distinctly modified (Plate LXVI, 27, b). Here 

 the branches of the network are themselves forked and their prongs are 

 extended as longitudinal rings; also, the transverse rings are more numerous 

 and irregular. Behind the operculum there is still another structure. 

 Over the network of the exochorion, and at first without any connection 

 with it, is formed a characteristic trellis of longitudinal and transverse 

 rings, having as a groundwork a narrow, undulating band whose curved 

 edges lie always on a furrow of the epichorion. The whole is then set 

 through with transverse parallel rings, some of which are found also between 

 the epichorion network. Directly behind the opercular furrow the chorion 

 extends as two specially large projections which bend forward and are 

 forked at their outer ends (Plate XLVI, 27, a). These are two lamellae, 

 which extend around the whole circumference of the egg, overarching 

 the furrow and protecting it. In the fully developed egg (Plate LXVI, 29) 

 the rings are said to be made of chitin and to have become a part of the 

 chorion. The remainder of the epithelium is now an amorphous mass 

 and is the so-called egg-white layer around the egg, of which Gross says 

 (page 370 of reference cited): " Auch dieser Umstand, dass der FoUikel 

 schliesslich sich zur Eiweisshiille umbildet, ist, soviel ich weiss, ohne 

 Analogon unter den Insecten." The epichorion is connected with the 

 exochorion anteriorly at the opercular ridge and posteriorly at the egg 

 stigma, a complicated structure whose significance is not clear. A diffusion 

 of air through the pores cannot take place because of the egg white. 

 An interchange of gas cannot take place, although the space between 

 the exochorion and the epichorion contains a quantity of gas; rather is 

 this chamber of gas to he regarded as a warm covering for the egg, or it 

 majr serve as a protection against injurj^ from blows to which eggs attached 

 to the hair of animals are exposed. 



In the egg of the hog louse the micropjdes are not indicated by any 

 special formation. In sections the}- can be seen as simple canals, narrowing 

 somewhat at their inner ends, in the vicinity of the operculmn. Leuckart 

 (185.5:141) did not state their number; according to Gross (1906:371) 

 there are at least thirty. 



