298 PHILLIPS—A REVIEW OF PARTHENOGENESIS.  [Oct. 16, 
generation (4), the emigrants. This generation goes to another 
plant and produces a third generation (c), the remigrants and sexu- 
para, which hibernate, return to the original plant and produce the 
small wingless sexual forms (@), the ‘‘sexuales.” Here the sexual 
generation occurs in the spring rather than in the fall, as in most 
other forms, 
Similar conditions are found in the Chermetidz, except that here 
the parthenogenetic generations as well as the generations arising 
from fertilized eggs are oviparous (see the works of Blochmann, 
Dreyfuss and Cholodovsky). In Chermes adietis the fertilized egg 
develops into a wingless parthenogenetic female (a@), which hiber- 
nates at the base of the buds of Adzes dalsamia and produces galls. 
In the spring winged females (4) are produced, which migrate to 
the Larch and give rise parthenogenetically to a wingless genera- 
tion (¢), which hibernates under the bark. These alienocole in 
the following spring produce parthenogenetic winged females (2), 
remigrants or sexupara, which return to Adzes and produce wingless 
males and females, the eggs of which produce the first generation 
named in the cycle. Here two years is required to complete the 
cycle. 
In Phylloxera quercus (Lichenstein) the winter eggs are laid on 
Quercus coccifera and give rise to females, which produce partheno- 
genetically a winged generation (emigrants), which fly to Q. pedun- 
culata and Q. pubescens. These parthenogenetically produce sev- 
eral generations of alienocole and finally produce the remigrating 
sexupara, which return to Q. coccifera and produce the sexual gen- 
eration. In Phylloxera vastatrix the generation which develops 
from fertilized eggs laid under the bark of the grapevine wander 
to the roots and there produce parthenogenetically several genera- 
tions of wingless forms, which cause the swellings of the roots. 
This series is closed by the production of winged sexupara which 
go to the surface and swarm. ‘Their eggs, which develop without 
fertilization, vary in size according to the sex, and the resulting 
individuals again begin the cycle. 
The physiological difference between fertilized and parthenia 
genetic eggs is often accompanied by difference in appearance. 
The parthenogenetic ones are generally small and poor in yolk and 
develop in a shorter time and in greater number, while those 
requiring sexual cell union are larger and develop more slowly. The 
former are called summer eggs or Sudctaneter; the latter winter 
