1970 年 83 巻 980-981 号 p. 67-73
Salvinia natans (2n=18) in the neighborhood of Hiroshima and Matsuyama are cytologically studied. Those having the same chromosomal component had two chromosomes which may be due to the reciprocal translocation. It may have occured between a segment from short arm of one of No. 8 chromosome pair and a segment from long arm of one of No. 9 pair in the standard karyotype as found in S. natans from Okayama (Tatuno and Takei6)), which will build up two new type chromosomes, namely, No. 16 (Tr1) and No. 17 (Tr2) as found in plants from Hiroshima and Matsuyama.
At meiotic metaphase I in S. natans from Hiroshima and Matsuyama, tetrapartite ring chromosome was formed by two normal (No. 15 and No. 18) and reciprocally translocated chromosomes.
As in the translocation heterozygote of other organisms, the separating form of the tetrapartite ring chromosome at meiotic anaphase I shows two types, i. e., ring and zygzag type, and the rate of the fertilized microspore was fifty perecnt in one microsporangium of the translocation heterozygote on S. natans.