Abstract
Since I published “Cytological Studies an Tropaeolum majus” in 1925, 1 have been continually engaged in the karyological investigation of more than 260 species, covering 82 families, including both Monocotyledons and Dicotyledons (cf. Table 1 in which 81 families, 250 forms including 233 species are listed).
1) Throughout the present study I have used modified Farmer's fixative exclusively for the fixation of materials of both flower buds and root-tips, and have had favourable results.
2) I usually found one more or one less chromosome in related plants instead of a polyploidal relation. In some Gases the cause of this seemed to be explained by chromosome fusion during diaphase.
3) In the plant groups investigated in the present work polyploidy and aploidy are both found. Discussion an these phenomena among others is left until further study an chromosome numbers in many more plants or plant groups has been made.
4) The chromosome sizes during meiotic and somatic nuclear divisions were measured (cf. Table 1).
5) True cell plate formation was not observed in the plants used in the present work.
6) Considering the works of previous authors together with the present Gase it may be concluded that the f urrowing process during the formation of partition wall of pollen mother cells prevails in the Dicotyledonous plants and is found also in some Monocotyledons.
The expense of carrying out the present study was partly defrayed out of a grant from the Educational Department, and from the Foundation for the Promotion of Industrial and Scientific Research of Japan, to the authorities of which the writer wishes to express his best thanks.
