Sex Determination in Phylloxerans and Aphids 291 
The abdomen and its eggs become so transparent in the xylol that 
the size of the contained eggs is readily made out. 
Most of the galls were closed except a few at the beginning and 
end of the series, as indicated by the small number of migrants 
present. Even in these open galls a few immature individuals 
still remain. In the galls in which a large number of winged forms 
are recorded the number of immature individuals is small. 
The 34 galls recorded in Table IV contained 4824 male pro- 
ducers and 1704 female producers (migrants) or 2.8 to 1. “There 
is much variation as to the number of eggs contained in each 
individual; the female-producers as a group containing fewer than 
the male-producers. If we estimate the male producers as averag- 
ing 16 eggs and the female producers 8 eggs, the proportion will 
Deny ier male.caes to—13,092 female cers, or 5:6 to 1. The 
excess of males is therefore again shown both by the presence of 
more male producers containing more eggs, as well as by the less 
exact estimate based on the supposed average number of eggs. 
TABLE IV. , 
MALE MALE 
FEMALE FEMALE 
PRO- IMMATURE PRO- IMMATURE | 
PRODUCERS PRODUCERS | 
DUCERS DUCERS 
9 I 9 open 32 I many 
8 24 54 open 106 2 = 
8 II 8 open 23 8 
120 I = closed 41 13 13 open 
13 331 = 16 5 10 open 
152 177 = 7 ° 3 open 
240 ° = 38 5 go open 
229 ° 295 36 3 63 open 
185 ° g2 209 II 53 opening 
219 29 = _ 278 ° 56 closed 
87 209 = Il 106 199 opening 
361 ° I 3 386 24 
127 ° = 383 4 31 closed 
390 14 = ° 328 II closed 
323 R = 40 ° 197 closed 
240 ° = 335 27 27 closed 
291 ° == 293 8 21 closed 
