54 



HEREDITY AND SEX 



Fio. 30. — Diagram of chromosomes in Phylloxera carycecaulis. Top 

 line, somatic cell of female with 6 chromosomes and somatic cell of male 

 with 5 chromosomes. Second line, stages in first spermatocyte division 

 producing a rudimentary cell (below) with two chromosomes. Third line, 

 second spermatocyte division into two equal cells. Fourth line, sexual 

 egg (3 chromosomes) and two polar bodies; and two functional, female- 

 producing sperm with three chromosomes each. 



