A CHROMOSOME STUDY OF THE APHID MACROSIPHUM SOLANIFOLII

Abstract

The parthenogenetic [female] has 10 chromosomes. The [male] has 9 chromosomes. Maturation of the parthenogenetic [female] egg consists of 1 equational division, which produces 1 polar body containing 10 chromosomes, while 10 chromosomes remain in the egg. During the 1st maturation division in the [male], 8 of the chromosomes pair and are drawn to the poles, while the unpaired chromosome lags. There results a large secondary spermatocyte with 5 chromosomes and a small one with 4 chromosomes. The large one divides equationally and the spermatids develop into mature, viable spermatozoa; the small cell degenerates.