86 GEOKGO ORIHAY SHINJI 



end. This substance was found literally filling the oviducts of 

 the adult during her egg-laying period. 



The presence of the yolk membrane cannot better be illus- 

 trated than by figure 28. On account of the migration of the 

 symbiotic organisms after the formation of the yolk membrane, 

 the latter is pushed in and remains separated from the chorionic 

 membrane (which is the last to envelop the egg). 



A fully matured egg with all its components is elongate oval. 

 The pointed end corresponds to the cephalic and the blunt end 

 to the caudal end of the insect. The ventral surface near the 

 pointed end is slightly indented. Thus not only the antero- 

 posteriority, but also the dorsoventraUty are marked in the eggs 

 of the coccids, but not so clearly as in the eggs of the Orthoptera 

 and Coleoptera reported by Heymons ('89), Wheeler ('93), and 

 others. 



Besides such a difference in shape, the anteroposteriority is 

 well marked by the presence of a dark-staining substance, the 

 position of which varies with the species. In cottony cushion 

 scale, it is, at first, visible near the posterior pole, but later 

 becomes pushed gradually toward the anterior pole by the 

 invaginating germ-band; while in the case of Pseudococcus and 

 Lecanodiaspis, it is found always near the anterior end of the 

 egg. The presence of these polar granules or symbiotic organisms 

 is a great service in the determination of the position of the 

 sectioned material. Later on, I shall treat of the history and 

 significance of this substance under a separate heading. 



No micropyle was found. 



The longest and shortest diameters of the eggs of the three 

 species of coccids are respectively as follows : 



NAME OF SPECIES 



Icerya purchasi 



Pseudococcus macdanieli. 

 Lecaniodiaspis pruinosa. 



8.5-9.0 



4.0 



6.0-4.0 



4.5-5.0 

 2.5 



2.5 



