Morphologically says, the ontogenic form of fern spores is defined on the bases of symmetry and polarity into two types: tetrahedral (trilate) type and bilateral (monolate) type. Basing on the topographic survey of sporal types in the system of ferns, the present author considers the evolutional trend of those two types: tetrahedral types→bilateral type. The state of revelation of those types in some species, genera, and families shows that this trend may have been progressing not only in the past but in the present time.
It will be necessary to classify fossil pollen on a level of species instead of genus for the purpose to obtain more accurate knowledges of paleoflora, paleoecology, paleoclimate and detailed correlation of sediments in which the pollen is contained. In this case, the size of pollen grains is considered to be important for the identification, particularly for the differentiation of a number of species within the same genus. It seems, however, that much prudence is apparently required in the treatment of the size of fossil pollen. In the present paper, the writer would like to show, with some illustrations of Tertiary specimens, that the size is not inherent for the pollen, but it changes after deposition even in a same genus by such factors as (1) chemical treatments to take out fossil pollen from sediments in which the pollen is contained, and (2) sedimentary conditions under which the pollen deposited.
Of 21 spp. the authoress counted the number of pollen grains in an anther and compared the number of grains in it and the size of each grain. The number of grains in an anther is various and found that there is much difference by species, such as <100-45, 000. The result of each sp. is shown in table I. In this table column “A” indicates an average number of grains in an anther of a species; column “B” the number of the grains in a flower, basing on the number in column “A”, giving the number of anthers in the parenthesis. Column “C” indicates total number of grains in the flowers on an inflorescence showing the number of flowers in the parenthesis. Column “D” indicates an approximate number of grains produced on some 20cm long branchlet or a scape, the figure in the parenthesis being the number of flowers. In the meantime, the writer paid an attention of the number of grains in an anther and their size. In this attempt the present writer recognized, excepting some exceptional cases, number of small grains far exceeds that of larger ones. The above is an observation based on a limitted species and material and it is not the writer's intention to propose as a final conclusion.
This paper deals with the pollen analytical studies of Quaternary sediments from Ogawara and Numasaki, near the lake Ogawara, Aomori Prefecture. Ogawara: In the upper layers of a peat columnar sample of Ogawara, Pinus and Cryptomeria are abundant. The deciduous broad-leaved trees, such as Fagus, Quercus, Carpinus, and Pterocarya tend to increase in the lower layers. Alnus occurs in a large quantity throughout the layers except for the surface. As to the non-arboreal pollen the dominant groups are Gramineae, Cyperaceae, Compositae, Polypodiaceae and Osmndaceae. Based upon the sequences of pollen mentioned above, the writer concludes that the upper layers of peat from Ogawara correspond to Period RIII (cooler period) in Nakamura's division of Japanese pollen records. The middle and lower layers refer to Period RII (warm period). Numasaki: The pollen flora of the peat and clay from Numasaki is characterized by the dominance of subarctic conifers, such as Pinus, Abies, Picea, and Tsuga. The temperate species are scarcely found in the upper layers. It can be said from these facts that the sediments from Numasaki are thought to have been deposited during the cold period in the Pleistocene.
(1) We examined the deposits of the Shimosueyoshi Stage in Kuninaka Plain (Sado Island) and Takada Plain in Niigata Prefecture in the light of pollen analysis and deduced the paleoclimate of that stage. (2) Paleoclimatic changes in the days of deposition are supposed to have been warm→cool or cool→warm in the Kuninaka Plain and warm→cool→warm→cool or cool→warm→cool→warm in the Takada Plain. (3) It may be said that the paleoclimate during deposition of each formation differed not greatly from the present climate.
Three palynological researches were reported in this paper: they are (1) the study on the typical late Tertiary system developed around Kanazawa and in the Aikawa-Sawane route in Sado Island; (2) the pollen analysis of the Diluvial deposits developed extensively at some localities of the district, (a) early Diluvial terrace deposits in Kanazawa, (b) late Diluvial marine terrace deposits around Hiradoko, (c) late Diluvial Okuhara marine terrace deposits near Nanao; (3) the investigation on the Alluvial deposits developed beneath the Imizu plain, Toyama Prefecture. A summary of the palynological studies on the late Tertiary deposits is shown on Fig. 1. The geologic profile of Hiradoko terrace (Fig. 2B), change of sea-level (Fig. 2A), several paleogeographic maps (Fig. 3, left), a series of schematic profiles (Fig. 3, center) and pollen assemblages in several stages of Hiradoko age (Riss-Würm interglacial age) (Fig. 3, right) will help for understanding the climatic change through Hiradoko age. A summary of the palynological studies on the late Pleistocene Okuhara formation and Alluvial deposits is shown in Figs. 4 and 5 respectively.
The writer aimed at the zoning of Alluvial deposit of Tokyo Bay, from the view point of pollen analysis. Two boring cores were obtained, one was at the Warf of Harumi, Tokyo, and another, KI-10 at a locality 5km off Hunabashi City, Chiba Prefecture (Fig. 1). These two pollen spectra are shown in Figs. 2 and 3. The lists of rare specimens are shown in Tables 1 and 2. The cores are lithologically classified in ascending order as follows: Diluvial silt, basal sand, lower clay, middle sand and clay, upper clay, and upper sand. They roughly coincide with Zone W, MW, A, C, T and P of pollen respectively, and are Alluvial except Zone W (Table 3). The climate of Zone W is considered to be cool as proved by the occurrence of such pollens as Abies, Picea, Tsuga, Fagus and Patrinia. The last one is said by Shimakura (1961) to be one of the indicator of a cool climate of Japanese Quaternary (see the Plate). In Zone MW the flora is gradually changing towards the lowest zone. Zone A shows a warm climate and characterized by Alnus which may be a local phenomenon. Zone C comprises abundant coniferous trees, mostly Cryptomeria. Therefore the writer assumes that the climate changed from warm to cool. Zone T is characterized by broadleaved trees (Tricolporo-pollenites spp.) indicating a warm climate similar to that of today. Pollens of recent Pinus are abundant in Zone P.
The sediments obtained from Itachino and Noichi locating at the low land, east part of Kochi City, were studied pollenanalytically. As the result of the pollen analyses of these profiles, 4 periods were recognized in the following order from the bottom: 1. Cool period (RI): The area of the Tsugion sieboldii Suzuki ('52) was extended. Its lower limit was lower about 1000m than it is now. This period was recognized at the bottom part of Itachino and the whole of the layers of Noichi. 2. Transition period (RI-II): This period is characterized by an invasion of Cyclobalanopsis. RI-II is regarded as a transition zone between RI and the next RII. In temperature it seems to be more or less warmer than that of RI, but lower than to-day. Therefore these two periods may be referred to the Lateglacial period and the temperate ecotone zone in climate. 3. Warm period (RII): The forest of the former period was pushed away by the warm temperate forest elements such as Cyclobalanopsis and Shiia which became dominant. 4. Decreasing warmth period (RIII): The mutual replacement in dominance of the conifers and the ever-green broad-leaved forest was noticeable. This may be referred to the pluvial stage. After this, sudden increase of Pinus up to the surface is recognized. It is a common phenomenon through out Japan.
In Ôita City, there are distributed the Sekinan and the Ôita groups which deposited during the late Tertiary and the early Quaternary. By pollen analysis of these deposits, the following results are obtained. 1) The floral changes of that time in this region are similar to those of the Ôsaka group and its equivalents of the other regions in Japan, and summarized as follows. a) At the middle part of the Higashiwasada formation (the middle part of the Sekinan group), among the Tertiary floras Nyssa becomes extinct, but Metasequoia is still found in this stage. b) The first appearance of Cryptomeria in this region is shown at the middle part of the Handa formation (the upper part of the Sekinan group). c) In the upper part of the Takio formation (the lower part of the Ôita group) Metasequoia has already disappeared, while Fagus becomes predominant. 2) The first cooling of the climate may be indicated by the appearance of deciduous Quercus at the middle part of the Higashiwasada formation. Therefore, it is presumed that this horizon indicates the Plio-Pleistocene boundary in this region.