Abstract
By using the squash method, researches on the karyotype of Phagocata teshirogii and chromosomal variations found in neoblasts of regenerating pieces have been carried out. Observations were also made on the meiotic divisions of primary spermatocytes and oocytes.
The chromosome number of this species was 2n=24 and n=12. The karyotype consisted of 5 pairs of metacentric chromosomes, 1 pair of subtelocentric and 6 pairs of submetacentric chromosomes (Table 2). Chromosome No. 1 is particularly large. Chromosome No. 2 is medium in size, while all the others are distinctly small (Fig. 3). Although many neoblasts in regenerating pieces have the chromosome number of 2n=24, some others have different chromosome numbers. This finding seems to support Chandebois' view that various kinds of abnormal cell division, such as amitosis, budding and endomitosis, occur in neoblasts during regeneration (1965, 1976). No abnormality in chromosome number was found during the meiosis of spermatocytes and oocytes.
