236 
Psyche 
[September 
production. Gabritschevsky’s observations were made in 
Russia so that geographically at least the two stocks of in- 
sects used are widely separated. However for the present, I 
am inclined to adopt the explanation that is presented in 
the investigations of Thomsen (’27) on Lecanium hemis- 
phxricum and Lecanium hesperidum. In both of these 
species there are two distinct races. In one race reproduc- 
tion is always parthenogenetic and no males are found. The 
other race however is facultatively parthenogenetic and its 
eggs are capable of fertilization or, lacking that, of parthe- 
nogenetic development. The cytology of the two races is 
radically different. I suggest that in Aspidiotus hederx 
also, there may be two races of this kind. The race that I 
have worked on reproduces solely through parthenogenesis 
and indeed, its cytology is in principle identical with the 
corresponding race of Lecanium. That the other race exists 
also is supported by the recorded occurrence of males as 
well as by Gabritschevsky’s findings, who may well have 
had a mixed population composed of both the races in 
question. 
References. 
Gabritschevsky, E. 
1925. Postembryonale Entwickelung, Parthenogenese und 
Pedogamie bei den Schildlausen (Coccidse). Russian, 
with German summary. Revue Zoologique russe, Vol. 3. 
Hughes-Schrader, Sally. 
1925. Cytology of hermaphroditism in I eery a purchasi 
(Coccidse). Zeitschr. Zellforsch. mikr. Anat., Vol. 2. 
Thomsen, M. 
1927. Studien liber die Parthenogenese bei einigen Coc- 
ciden und Aleurodiden. Zeitschr. Zellforsch. mikr. Anat., 
Vol. 5. 
