MALE AND FEMALE EGGS OF PHYLLOXERANS. 203 



ber of such cases in which the number of the chromosomes could 

 be counted with perfect accuracy. In Phylloxera globosnm there 

 are only six chromosomes in the polar spindle (Fig. i), which 

 makes it a very favorable object for study. In all eggs in which 

 the chromosomes could be counted the same number was found, 



FIG. 2. Phylloxera sp. ? Left hand figure is a spermatogonial equatorial plate. 

 Right hand figure is from a somatic cell of a male embryo. 



and this is true both for male and for female eggs. In this re- 

 spect there seems to be no difference between the two kinds of 



eggs- 



In Phylloxera sp. ? the number of chromosomes in the male 



and female eggs seems to be twelve (Fig. 2). It is more 

 difficult to count so many chromosomes with accuracy, at least 

 in the eggs that I have so far seen ; but as the clearest cases ob- 

 served showed twelve chromosomes, and as in other eggs eleven, 

 or twelve, or thirteen seemed to be present, and since the num- 



: 



FIG. 3. Phylloxera sp. ? Spermatocyte divisions. Equatorial plates. Upper 

 row, first spermatocyte divisions ; lower row, second divisions. 



ber of chromosomes in the spermatocytes is definitely six (Fig. 

 3), there can be little doubt that the number in the polar 

 spindle is twelve. In Phylloxera cary<z-globnli there are twenty- 



