Seasonal changes of photosynthetic activity of leaves in Zelkowa serrata (a deciduous tree) and some evergreen trees, were investigated and meaning of concerning dry matter production was discussed. 1. The photosynthetic activity of Zelkowa increased rapidly up to its maximum value of 5-6mg. CO2/50cm2./hr. later in April and the value persisted for about 2 1/2 months; afterwards the activity decreased slowly until the defoliation in November. The activity maintained itself above a half value of the maximum for about 4 1/2 months of which mean monthly temperatures were above 17°. The photosynthetic activity changed fairly parallel, but only apparently, to the chlorophyll content. 2. In late spring and summer, the courses of change in the photosynthetic activities in evergreen trees, Shiia Sieboldi, Pittosporum Tobira and Cinnamomum Camphora, were more or less similar as that of Zelkowa. In late autumn the activity fell to a low level, and it continued throughout the winter, and only in Pittosporum the activity recovered before the leaf fall in next late spring. 3. The younger stage of leaf is characterized with a higher respiration and compensation point, and with a lower chlorophyll content and photosynthetic activity. These were clearly shown in the leaves of a Lammas shoot which have generally higher activity than those of ordinary shoot. 4. The weight of the leaves of Shiia and Pittosporum is ca. 180g./m2., while that of Zelkowa is ca. 90g./m2., hence, to get back these invested capitals the former species must earn about double amount of dry matter. In southern districts this may be easily realized in warmer winter, and which makes the evergreen tree more advantageous in competition with the deciduous tree in natural distribution.
1. The mucilage which surrounds the egg of Coccophora Langsdorfii is stained with Congo red, with ruthenium red, and with ferric chloride preceded by treatment with tannic acid. 2. The mucilage is composed of the inner membrane, the middle layer, and the outer mucilage. The inner membrane has a number of small pits. The middle layer consists of many sublayers. The outer mucilage cannot be stained with any of the above agents. 3. The axle of the mucilaginous stalk is stained red, and its surrounding zone deep blue-violet with Congo red. This reveals a positional relation between the egg and the stalk. It is known that the form of the elongated egg is controlled by the pressure, perpendicular to the stalk, of the inner membrane, so that the polarity axis of such eggs is determined parallel with the stalk.
1. As the material the Japanese radish was used. 2. Retardation of the growth of the growing point by embedding in gypsum causes flower-initiation to some extent, though the plant is not exposed to cold. 3. Retarding the growth of plumule by application of malefic hydrazide solution to it, causes flower-initiation in some measure, though the plant is not subjected to low temperature. 4. Inhibition of vegetative growth by using hypertonic sugar solution leads to flower-initiation in some degree, in spite of no cold-treatment. 5. The writers advance a speculation that the aging of the protoplasm in the tissue of the growing point is probably favourable to inducing flower-initiation.
1) When two successive dark periods of subcritical duration-for example 8 hours -are applied successively to the apical and then immediately hereafter to the basal half of the same leaf, and this is repeated for several days, no flower primordia or a few only are initiated. The above mentioned effect is very weak in contrast to plants in which the basal or apical half of the leaf is subjected daily to one dark period of two fold duration-for example 16 hours. Two successive inductions caused by dark periods of subcritical duration applied to two different parts of one leaf can initiate a considerable number of flower primordia only when the plant used has high sensitivity. 2) The effect of two dark periods of subcritical duration given successively to two adjacent leaves is not so effective as the application of a dark period of double duration to one leaf. 3) The phenomenon may be explained by the assumption that the reaction taking place in the dark does not proceed linearly in relation to the duration of darkness but has a pronounced lag phase. 4) In contrast to Perilla and Xanthium, no significant difference could be observed in Pharbitis Nil, between the dark treatment of sufficient duration to the apical and to the basal half of a leaf.
The relation of photosynthesis of natural phytoplankton to each environmental factor was discussed in detail on the basis or laboratory experiments. 1.In eutrophic lake water, or in water enriched with nutrient salts, light saturation of photosynthesis occurred at about 15klux. in Cyanophyceae communities, at about 10klux. in Chlorophyceae, and at 7klux. in Bacillariophyceae. Such light saturation, however, was found at low light intensity of about 4klux. with phytoplankton in oligotrophic lake water. 2. The highest photosynthetic activity of phytoplankton of about 8mg. O2/chl. mg./hr. was measured in natural waters of eutrophic lakes. The activity in mesotrophic lake was about 4mg. O2/chl. mg./hr. and the lowest was 2mg. O2/chl. mg./ hr. in oligotrophic lakes. 3. The effect of supply of nutrient salts on photosynthesis of phytoplankton was not so remarkable in eutrophic lake waters as in oligotrophic ones. However, nutrient materials in water were exhausted sometimes even in eutrophic water in summer and autumn, and the deficiency in such materials would be able to limit the primary production of lakes severely. 4. Potential photosynthetic activity of phytoplankton was almost constant throughout the year, except for two spells in March and in August when heavy altering of constitutent phytoplankters were going.
1. The vacuole appears according to the condition in which the yeast-cell exists. 2. In the vacuole there are nucleolus-like body, toluidine-blue stained bodies and neutral red stained bodies. They are recognized when adequate staining method is used. 3. The nucleus is attached to one side of the vacuole and contains centrochromatin which changes into chromosomes in mitosis. 4. At the prophase of mitosis the centrochromatin changes into two chromatinic bodies. Sometimes the nucleus shows spireme in its interior. At metaphase the nucleus changes into four chromosomes which sometimes conjugate two by two. 5. At the metaphase the chromosomes appear in the spindle which is situated on the surface of the vacuole. So the chromosomes overlap on the intravacuolar bodies.