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Psyche 
[September 
pleted more quickly on Aucuba than on Hedera and palm. 
In any other group of insects, this evidence might be 
deemed sufficient to demonstrate that parthenogenesis 
occurs in the species. But it must not be forgotten that it 
is in the Coccidae that a case of functional hermaphroditism 
is encountered (I eery a purchasi, one of the Monophlebinae 
as reported by Hughes-Schrader, ’25). 
In such an instance no breeding experiments of the type 
I have described will in themselves settle the question. 
Only a cytological examination would finally decide the 
point and such an examination was made in Aspidiotus. 
This shows that not only is there no internal evidence of the 
presence of any male tissue in the females, but also that 
the maturation and development of the eggs follow a series 
of steps which is typical of so-called diploid partheno- 
genesis. 
The somatic cells of immature as well as mature females 
carry 8 chromosomes. In the course of maturation of the 
egg, 8 chromosome threads are formed and these show no 
trace of bi valence or tetrad structure (Fig. 1.). 8 chromo- 
somes also appear in the stages of final condensation (Fig. 
2.) so that evidently there is no pairing of the chromo- 
somes. Only a single meiotic division takes place and this 
is equational in nature, 8 chromosomes going to each pole. 
Apparently the polar body is not actually extruded but re- 
mains at the periphery while the egg nucleus migrates 
toward the center of the egg (Fig. 3.). Further divisions of 
this egg nucleus occur in a quite normal manner and the 
cleavage nuclei all carry 8 chromosomes. (Fig. 4.). 
It is plain that taken together, the experimental and 
cytological evidence demonstrate that in this particular 
stock of Aspidiotus hederse reproduction is parthenogenetic 
and normally results in nothing but females. But it would 
be rash to generalize on this basis. Males have certainly 
been described for the species and as mentioned above 
Gabritschevsky reports that males were produced on some 
of the plants under his observation. Indeed it may well be 
that some stocks of the species are more susceptible to 
environmental influence than others and that in such cases 
the host plant may drastically affect the process of re- 
