抄録
Cytologically Halys dentatus and Halys sp. differ in the staining reaction of the nucleolus which is, however, formed by the heteropycnotic ends of the autosomes in both the species. It appears that the staining difference between the two is of the same nature as that of the heterochromatin which shows positive or negative reaction at different stages during the life of a particular cell. The metrical analysis of the chromosomes at metaphase I reveals that the difference in the chromosome sets of the two species is of the nature of a single homozygous deletion or reduplication in the longest pair of the chromosomes. It has further been observed that there is a continuous decrease in the total length of the monoploid genome during the successive spermatogonial generations which is also accompanied by the decrease in the area of the cell. There does not, however, appear any correlation between the two.
