SEX INHERITANCE 



101 



One of them, XxXx, produces eggs which, after 

 extruding one polar body, give rise to the migrants 

 bearing large eggs; from the latter eggs, in turn, come 



XxX: 



3TEM MOTMEK-ninALE PRODUCING LINE 



1" GENERATION 



XxX 



X' 



5T01 MOTHER - MALEPRODUONG LINE 



XxXx 



POLAR SPINDLES 



STEM MOTHER'3 ECG5 



XxX; 



MIGRANT -FEHALE PRODUCER 



FEMftLE EGG 



XxXj 



fEMALE 



2"" GENERATION 



XxXx' 



MIGRANT.- MALE PRODUCER 



SEXUAL EGG 



XX 



XX' 



POLAR SPINDLES 



MALE EGGS 



3"' GENERATION 



X, 



.X 



MALE . TYPE I 



Xx' 



MALE. TYPE n 



POLAR SHNDLE 



FEHALE PRODUCING 

 SPERH 



DECENEfWTE 

 ■ 5PERM " 



FiQ. 35.— 



Diagram to illustrate the chromosomal cycle of Phylloxera 



caryaecaulis. 



