2, PAULINE H. DEDERER 
been demonstrated by Morrill (09) for certain coreid Hemiptera, 
by Morgan (’09) for phylloxerans, by Stevens (06 a, ’09) and 
von Baehr (’08, ’09) for aphids. 
In studying the history of the male germ cells in the moth 
Philosamia cynthia (Dederer ’07), the spermatocytes were 
found to contain exactly similar groups of chromosomes. ‘The 
same facts had been determined by Stevens (06 b) and Cook 
(10) for various other Saturniidae. Doncaster (’12) believes 
that in Pieris brassicae there is no dimorphism, either in the 
male or female germ cells. Recently, however, Seiler (713) 
has decribed two kinds of eggs in a lepidopteran. ‘These two 
papers will be discussed later. The present work was under- 
taken with special reference to the question of dimorphism in 
the eggs. I wish to express my indebtedness to Prof. E. B. . 
Wilson for valuable advice and criticism during the course of 
the investigation. 
MATERIAL AND TECHNIQUE 
Carnoy’s aceto-alcohol-chloroform mixture, saturated with 
sublimate, was used almost exclusively, since it readily pene- 
trated the tough chorion of the eggs, which were left in the 
fluid from two to four hours. Flemming’s and Bouin’s fluids 
were used, but proved very unsatisfactory. The eggs were then 
transferred to iodized 95 per cent alcohol, and the chorion was 
removed with needles. After dehydration in absolute alcohol, 
the eggs were placed in a mixture of alcohol and chloroform fol- 
lowed by pure chloroform for ten minutes. Immersion in melted 
paraffine for fifteen minutes was sufficient for perfect infiltra- 
tion. The stains used were iron hematoxylin, and in a few cases 
safranin. 
The maturation spindle remains in first metaphase until 
the entrance of the sperm. The following. tabulation gives 
roughly the maturation stages at different intervals after the 
eggs are laid: 
Eggs just laid to 3 hour laid first anaphase 
Eggs laid 1 to 14 hours second metaphase 
Eggs laid 12 hours second telophase 
Eggs laid 2 to 2? hours fusion of pronuclei 
