168 Schrader. 
cocoon which is so characteristic of other species and instead hides 
away in such places as the old egg sacs left behind by the females. 
As many as twentyfour males have been found in such a location. 
All these sources of error were eliminated in the breeding 
experiments and the much larger proportion of males is thereby explained. 
I feel safe in concluding that at least in the species under consideration, 
random counts do not give the true sex ratio, and that the sexes are 
present in approximately equal numbers. 
The preceding data were obtained from Pseudococeus eitri, chosen 
for that purpose because of the greater ease with which it is procured 
and reared. In the cytological work which follows, another species, 
Pseudococeus maritimus, was found to agree with Pseudococeus eitri in 
all essential points; and at several stages it furnishes more favorable 
material from the technical viewpoint. However, since the breeding 
experiments had been made entirely with Pseudococeus estrı, it was 
thought best to present all of the cytological evidence from the same 
species. : 
CARNOY’s and KAHLE’s fluids were employed for fixation of all 
the stages concerned. It may be remarked that in the stages up to 
and including the first two divisions of the polar nucleus, the cytological 
evidence was not considered unless every section of the egg under 
examination was available for study. 
Maturation and Fertilization. 
The problem was attacked from the standpoint of cytology as well 
as by breeding experiments. The maturation stages were worked out 
very carefully, the work having been begun on the hypothesis that 
parthenogenetic development may occur. In view of the phenomena 
observed in the spermatogenesis of Pseudococeus (SCHRADER, 1921 
and 1922) as well as in consideration of the object with which the 
investigation was begun, a short account of the maturation is in order. 
Ten chromosomes are present in the oogonia. At the close of 
the growth period five tetrads are found. These, primarily very large 
in size and typically in the form of crosses (Fig. 1), then undergo a 
period of condensation (Fig. 2 and 3), and are finally identical in size 
and shape. The whole maturation takes place in a peripheral area 
of protoplasm, situated midway between the anterior and posterior ends 
of the egg. 
