254 T. H. Morgan 
bodies are given off, one chromosomal division being equatorial, 
the other reductional, in the ordinary sense, 1. e., the reduced number 
of chromosomes appears; so that two of the sex chromosomes pass 
into one of the polar bodies; their partners remaining in the egg. 
The egg having two accessories gets two more accessories from the 
functional spermatozoon which accounts for the four accessories 
that our analysis calls for. 
SEX DETERMINATION IN PHYLLOXERA CARYACAULIS 
The life cycle in this species is typical of the group. The chro- 
mosomal history is as follows: ‘The polar spindle of the stem- 
a B C 
D ;: > 
a 4. Se Ze 
e a / F 
Fig. VIII A-#, chromosomes of embryo from stem-mother’s egg. H, shows only two chromo- 
somes, for size relations. 
mother’s egg contains six chromosomes of nearly equal size 
(Fig. VII, 4, B, E-N, P, S). These eggs give off a single polar 
body (Fig. VII, C). 
The cells of the embryos contain six chromosomes, as shown in 
Fig. VIII, 4—f. It is a point of some importance to know 
