Abstract
The author has studied a hybrid produced by crossing M. viridis L. Subsp. crispata BRIQU. (8x= 48) and M. rotulrdifolia (L.) HUDS. (4x=24) with the respective cytological characteristics of autooctoploid and auto-tetraploid (TSUDA 1954, 1956). Morphologically two different types were prod-uced in F1 ; " Type I" being of maternal chara-cterrstlcs and "Type II " paternal. Hence it is assumed that one or both of the parents were mendellian hybrids. Somatic chromosome numbers were found to be 36 in both types (Fig. 1). Investigations on meiosis were carried out on Type I and the results obtained can be described as follows. 1. The coexistence of quadrivalents, bivalents and univalents at diakinesis (Table I and Fig. 2) is considered to be the direct cause for the varying number of chromosomes (23 to 1.4). 2. At the first metaphase, the chromosome numbers varies from 22 to 13 for the same reason as mentioned above (Table 2 and Fig. 3). Secondary associations of two bivalents and of two to four univalents were also observed. 3. Unreductive divisions were observed occasionally at first metaphase. 4. Chromosome numbers counted at second metaphase varies from 24 to 13, but total chromosome numbers fcund in two nuclear plates of one P.M.C. are generally higher than the usual somatic chromosome number, 36.
