Abstract
Cytological effects of 5-bromouracil were observed in germ cells of Podisma sapporense. Most frequent chromosomal abnormalities were chromatid-breaks and erosion. Cells showing those aberrations were observed rather frequently in, and particularly limited to, the division of the secondary spermatocytes 20 to 60 minutes after chemical treatments. The position of breaks appeared rather constantly in the same chromosome and tended to localize on a point one-fourth of the chromosome adjacent to the centromere. The chromosomes with breaks divided in normal manner at anaphase. The rate of division tended to decrease in affected material for a long period of time.
