The present paper deals with the analysis of the germination regulating mechanisms of Abrus precatorius L. seeds. The seeds occur in two forms viz., large and small. Dormancy in these seeds has been observed to be due to a seed coat which offers impermeability to water as well as mechanical resistance to the expansion of the embryo. One possible mechanism involved in breaking the seed coat dormancy in this plant may be desiccation to the extent of 7.31 percent, which promotes the germination up to 40 percent and 45 percent in large and small seeds respectively. Imbibition and desiccation both appear to be more critical for germination of small seeds than that of large seeds. Under light incubation sulphuric acid treatment for 120 minutes gives 80 percent germination in large seeds, and that for 90 minutes gives 90 percent germination in case of small seeds. Acid scarified seeds when subjected to continuous irradiation with red light give 100 percent germination at 25 and 30℃.
The main events experienced by the fish belonging to each population are schematically summarized in Fig. 1., basing on all the results given in the previous reports. Concerning the variations in the body form and the numbers of fin rays found in each population, it was suggested that these characters in question would be influenced by the environmental factors differently according to the developmental stages of the fish concerned. Through the morphological comparisons on the degree of the ossification of the skulls as well as the ring formation of the scals of the sea-run and the landlocked Ayu-fish, it was confirmed that the latter would be the form which suppressed their growth to some extent. However, the landlocked form can be considered to have relatively higher fecundity comparing with the sea-run form, because of their earlier spawning period, the ova with smaller diameter and more numerous in number. The dwarfism, and the early maturation of the present landlocked form coincided with the general tendencies already pointed out by many previous authors who studied several other species of landlocked fishes. Some considerations were made on the relation between the intra-species differentiation of the present species and the geological history of the lake.
The transition of germination capacity of seeds from 37 species of mature grasses gathered late in autumn was investigated during storage in the natural dry atmosphere at room temperature for a year. 1) The seeds of the following seven species did not germinate. Paederia scandens, Trichosanthes cucumeroides, Clematis apiifolia, Villebrunea frutescens, Phryma leptostachya, Dioscorea japonica, Cardiocrinum cordatum It may be considered that these seeds did not germinate because of the storage in the dry condition, but this needs confirmation by more experiments. 2) The seeds of 30 species germinated, and they were classified into the following six groups : A. Adenocaulon himalaicum-type ; The seeds of this type germinate soon after harvesting, but they lose the ability to germinate as time goes and finally they can scarcely germinate. ……Adenocaulon himalaicum. B. Epilobium pyrricholophum-type ; The seeds of this type germinate soon after harvesting, but their germination capacity lowers as the air temperature lowers. They regain their ability with the warm season spring. Their germination capacity reaches a peak towards May ; it again lowers in and after August. ……Picris hieracioides var. japonica, Adenostemma lavenia, Hosta minor, Plantago asiatica, Epilobium pyrricholophum. C. Sonchus oleraceus-type ; These seeds germinate soon after harvesting, and they continue germinating even after the climate becomes cold, until they gradually lose such ability in and after August. ……Aster hispidus, Lactuca denticulata, Erigeron canadensis, Sonchus oleraceus. D_1. Polygonum cuspidatum-type ; These seeds do not germinate immediately after harvesting, and follow the same course as the Epilobium pyrricholophum-type, beginning to germinate with the warm season of the next spring. ……Stellaria aquatica, Melilotus suaveolens, Perilla frutescens, Crassocephalum rubens, Polygonum filiforme, Isodon japonicus, Polygonum cuspidatum, Setaria chondorachne, Eclipta alba, Isodon inflexus, Ligularia tussilaginea, Solanum lyratum. D_2. Cyperus Iria-type ; These seeds begin to germinate towards the next warm season just as the Polygonum cuspidatum-type, however, their germinability changes with the air temperature and reaches a peak in the hottest season. The seeds of this type germinate fairly well towards the end of autumn. ……Corchoropsis tomentosa, Justicia procumbens, Phyllanthus Urinaria, Cyperus Iria, Carpesium cernuum. E. Digitaria adscendens-type ; Though the seeds of this type begin to germinate towards the next warm season as the last two types mentioned above. These seeds nearly retain the power to germinate up to the end of autumn from about May. ……Cosmos bipinuatus, Kummerowia striata, Digitaria adscendens. Although we can predict several factors that would bring into existence the above types in relation to the dormancy, such the temperature during the preservation and experiments on the seeds, and the length of time preserved, these factors should be ascertained by experiments. 3) As a rule, the groups that do not need dormancy and the groups that need only short dormancy reduce the germinability in and after the next August, and there are many species that show a high ratio of germination in and after August in the groups that seem to have long dormancy. Few annual plants, as a rule, belong to the Adenocaulon himalaicum-type, Epilobium pyrricholophum-type, Sonchus oleraceus-type, and the Polygonum cuspidatum-type, which lose germinability, and most of them belong to the Cyperus Iria-type and the Digitaria adscendens-type, which keep up germinability in and after August.