The sex ratio and oogenesis of Pseudococcus citri. 173 
cells growth is more rapid, but on the other hand, divisions are also 
more frequent. As a consequence the size difference characterizing the 
earlier stages of the two types of cells, still holds (Fig. 20 and 28). 
The Symbionts. 
At this point it is necessary to go back to the earlier history of 
the egg. Apparently the eggs of all Homoptera contain symbiotic 
organisms or mycetocytes, which are transferred from the body of the 
mother into the egg during its growth stages. These symbionts have 
been described for Pseudococcus in detail by such workers as PIERANTONI 
(1910, 1913), BUCHNER (1912, 1922), EMEIS (1915) and SHINJI (1919). 
In the mature Pseudococcus egg they are always located close to the 
anterior pole or point of attachment of the egg in the ovary; and are 
contained in a number of spheres of approximately equal size. These 
spheres may in turn be surrounded by an apparently noncellular mem- 
brane, but this condition, contrary to PIERANTONTS report, I find to 
be less common than a state of loose aggregation. EMEIS believes that 
only some eggs are thus infected, but in the examination of many 
hundreds of eggs I have never found one without them. In addition, 
I can agree with SHINJI, who states that the symbionts are found in 
the adults of both sexes, but like PIERANTONI I have found them 
less developed in males than females. In the adult female they exist in 
characteristic masses in close association with the ovaries. Further- 
more, they are always centered around very peculiar cells, the amoeboid 
processes of which hold them in a radial arrangement—the whole 
forming the so-called “corpus ovale” of PIERANTONI. At rare intervals 
there is mitotic division in these cells, and at such times it can be 
definitely established that they carry a multiple number of chromo- 
somes— probably more than forty on fifty (Fig. 25 and 26). These 
cells are, however, left behind and not transferred to the eggs with 
the spheres, an observation also made by PIERANTONI. During the 
eleavage stage of the egg, the group of symbionts remains close to the 
anterior pole, but at about the time when the giant cells are replaced 
at the periphery by the normal blastoderm cells, it sinks a short 
distance towards the center of the egg. 
The mass of giant cells now begins to move toward the anterior 
pole of the egg. Although remaining well grouped together, this 
migration is due to amoeboid movement of the individual cells. The 
path taken by the whole mass may be directly through the egg toward 
