78 GEORGO ORIHAY SHINJI 



time of hatching. Thus the experiment went along with promise 

 of success until several of the eggs supposed to be of the same age 

 were fixed and mounted in toto. The examination of these 

 prepared specimens, however, showed that no two of them were 

 in the same stage of development. One of them contained an 

 embryo nearly ready to hatch, another had an embryo with its 

 appendages well recognizable, while the remainder were mostly 

 in much earlier stages. 



Sectioned material of several adult females of both the mealy 

 bug and cottony cushion scale brought to light the fact that 

 the eggs of these two species of coccids undergo a partial devel- 

 opment in the uterus of the female. The early deposition of 

 the egg was usually noticed in specimens in which the growth of 

 the ovarian eggs was in rapid progress. The eggs were not 

 deposited until the completion of the blastoderm. The eggs of 

 the Lecaniodiaspis, on the contrary, were deposited at the first 

 cleavage stage, and should serve as the most desirable material 

 for this purpose. Unfortunately, I have failed to work with this 

 species during the past year. 



Thus the determination of the age of the eggs by the experi- 

 mental method alone is not reliable. Therefore the relative ages 

 of the embryos in this study were mostly determined by the 

 number of cells, the position of the polar granules, the length of 

 the embryo and of the appendages, and other morphological 

 features. 



Most of the material for embryological study was obtained 

 from egg-sacs of the fully matured female scales in the following 

 manner: Several females with their egg-sacs were collected at 

 various times of the day, and the egg-sacs were separated from 

 the body with a sharpened bamboo stick or needle. In some 

 cases the eggs were lightly shaken out of the egg-sac into a watch- 

 glass containing the fixing fluid, but in many cases the entire egg- 

 sacs were dropped directly into the watch-glass containing the 

 fixing fluid, and the cottony substance was removed afterward 

 with a pair of sharpened bamboo sticks. The use of sharpened 

 bamboo sticks proved to be advantageous, for they can be made 

 of anj^ desired sharpness and they are not acted upon by such 

 corrosive mixtures as Gilson's. 



