MATURATION OF MALE EGGS IN APHIS. 



73 



This year an unusual number of the apterous, male-producing 

 individuals were secured. Some were fixed and sectioned, others 

 dissected and the eggs and embryos studied in Schneider's aceto- 

 carmine. The sections gave no favorable stages. Out of a large 



Fig. I. Equatorial plate of maturation mitosis of male aphid egg. Outline of egg 

 and membrane shown above, x, the double chromosome. Zeiss 1.5-6, cam. 



number of aceto-carmine preparations, one egg was found which 

 had the maturation spindle in metaphase. This was taken from 

 an individual in which the older embryos were certainly male. 

 The equatorial plate contained nine chromosomes, ten being the 



Fig. 2. Same equatorial plate drawn -with Zeiss 1. 5-12. 



Fig. 3. Nucleus of embryonic cell ( ^ ) in prophase. x, the unpaired hetero- 

 chromosome. Zeiss 1.5-6. 



Fig. 4. Male embryonic cell in metaphase. x, the unpaired heterochromosome. 

 Zeiss 1. 5-12. 



number in non-sexual parthenogenetic eggs ('05, PI. I., Figs, 

 7 and 12^). This metaphase is shown in Figs, i and 2. The 

 chromosome in the center of the group is the double one. In 

 the first spermatocyte the lagging heterochromosome is the 



' " A Study of the Germ Cells oi Aphis rosce and Aphis oenofhetcF^" Jotirn. Exp. 

 ZooL, Vol. II,, No. 3, Aug., 1905. 



