Among the plant fossils from the Penhsihu coal fields, Manchuria, the seeds similar to or identical with Samaropsis affinis and fronds similar to or indentical with Pecopteris arborescens are found abundantly, both of which have been already found and described from the same coal fi lds. Therefore, it is not worth while to denote that two kinds of these fossils are found in this locality, but it is very wonderful that the specimen, in which the seed is borne on the pinna axis of the frond, has been collected. Though the example showing such a character is only in one specimen, the organic connection of both organs is so distinctly shown that this seed should be th reproductive organ of the Pecopteris frond. Pecopteris arborescens and Samaropsis affinis should be, therefore, the vegetative and reproductive organs of one and the same species, for which a new name Pecopterissamaropsis may be given. This sp cies is one of the best examples of the seed-bearing Pteridosperms. Pecopteris samaropsis Ogura, nom. nov. Seed-bearing fern-like plant; seed with type of Samaropsisaffinis borne on frond with type of Pecopteris arborescens. Collected by Dr. R. Endo from the Tsaichia Series (Upper Permian) of Sanchiahui, Penhsihu coal fields, Manchuria. Type in the Botanical Institute, Faculty of Science, University of Tokyo.
1) A Prasiola species, which is probably Prasiola japonica Yatabe, is obtainable all the year round in the Mitsusawa, a tributary of the Iri-river in Okutama area near Tokyo. The plant is monoecious, having the sori of both macro-and microgametangia in mosaic arrangement. The liberation, of both gametes takes place in late October (water temperature is 11-12°C) and continues until ate April next year (water temperature is 10-12°C), the best condition being found in February. Between April and June, fronds of old generation and those of the following generation are found simultaneously. In this species the asexual reproduction occurs chiefly from spring to autumn, about which report will be made elswhere. 2) Special attention was paid to the mode of liberation of the macro-and microgametes from the both gametangia. The number of the macrogametes formed in each macrogametangium is 16 in two groups of 8: that of the microgametes is 64 or 128 in each microgametangium. The liberation of gametes, can clearly he observed when a plant with ripe gametangia is floating on the surface of a tall container. The greenish masses of both gametes are included in mucus substance and sink slowly to the bottonn in streams. The macrogametes are discharged from the frond in a group of eight as they are in gametangium and after they are scattered and conjugates they scquire motility. On the contrary, the microgametes are in motion already in the microgametangium and when liberated they are in active movement. While the zygospores and microgametes are actively moving, they are pear-shaped having two flagella. In the zygospores it is difficult to observe twe flagella at the posterior ends, unless they are fixed and stained. In the microgamete, however, two flagella are clearly seen while in active motion. After they begin to swim the zygospores mesure av. 8.2μ in length and 4.4μ in breadth. While the microgametes are av. 3.9μ in length and 2.8μ in breadth. It is very remarkable that the portion of the zygospore near the flagella i beak-shaped and transparent. In Ulotrichalis the swarmer swims with the flagellated end forward. Both zygospores and microgametes of this species rotate clockwise and advance with the flagellated end backward. Both gametes do not show phototactic reaction. 3) As soon as the motionless macrogametes are liberated from the frond, the motile microgametes throng around them and unite with them by their flagellated ends. The zygospores then begin to move in the characteristic way. Consequently, the macrogametes in the swimming condition are hear regarded as the zygospores. 4) The zygospores attach themselves immediately to the substratum with their non-flagellated ends and become spherical, measuring av. 6.1μ in diameter. The zygote keeps on increasing in size up to av. 12.4×19.6μ. The resting zygospore begings to germinate and the cell divides transversely into two. By further cell-division and elongation the young sporeling develops into either three or four-cells. Two or three of the cells begin to protrude and form primary rhizoids. The longitudinal division of the vegetative cell begins to take place after from five to eight successive transverse divisions. 5) Studies on taxonomy of Prasiola are being made in the ligh of the observed facts.
1) Sampling methods in the statistics of plant communities are 1°purposive selection by some standard areas 2°random sampling by the theory of large samples 3°random sampling (areal sampling) by the theory of small samples. We have used the first or second method till now but in plant ecology we are ought to use the third method from now on. 2) From the theory of small samples, the confidential interval of population mean is x+d_??_m_??_x-d, d=τu/√N (d is the deviation of the sample mean from the populatin mean under the level of significance α) The h=d/x will become an indicator of the homogeneity of a plant community. For example, I calculated “the coefficient of homogeneity” to study various distribution of species on the Ophioglossumthermale-Imperata cylindrica var. Konigii-soc. at Futtu sea-shore of Chiba pref. 3) We can know the homogeneity of distribution of a species by the coefficient (h) and then deside the number of sampling quadrats to estimate an analytical character of a community.