XIV.—Male Haploidy and Female Diploidy in Sirex cyaneus F. (Hymen.)

Abstract

Summary1. From the above it is therefore justifiable to conclude that Sirex cyaneus is typically hymenopterous, in that:(a) the ripe male reproductive tissue is haploid (8 chromosomes), while the female oogonia are diploid (16 chromosomes);(b) the abortive character of the first spermatocyte division is evidence that chromosome reduction does not occur during the maturation of the male gametes.2. Support is thus afforded to the hypothesis commonly held, that the male hymenopteron is a haploid organism and is the product of an unfertilised (haploid) egg, while the female is a diploid organism arising from a fertilised egg.3. Feulgen's “Nuclealreaktion” holds for the chromatin involved in the abortive division and for the chromosomes of the second spermatocyte; but the large chromatoid body and cytoplasmic granules seen in these same stages by the iron hæmatoxylin technique did not give the chromatin reaction. The nature of these chromatoid bodies remains to be discovered.