Eggs of Coccophora Langsdorfii were cultured after being ultracentrifuged at 25000 time gravity for five minutes at the time before and 1, 10, 15, and 20 hours after fertilization. As a result, the following was revealed. (1)When the plastid layer is stratified in apical regions of the egg after transformed to ovate forms, the rhizoid cannot be formed. However, when the same layer is stratified laterally or in basal regions, normal rhizoids are differentiated at the basal, i.e. the pointed end. (2) Therefore, distribution of the intracellular materials is a factor in the actual formation of rhizoids. But, as the site of the nucleus stratified is not concerned with this, distribution of certain components of the cytoplasm seems to take part in the rhizoid differentiation. It is, however, not the only factor. It seems that (a) the site of the rhizoid differentiation is determined by the cortical layer of the cytoplasm immovable by centrifuging and (b) its actual formation is performed by a certain kind of cytoplasmic elements movable by centrifuging. (3) When the egg is centrifuged at two-cell stage or later, the rhizoid formation is not influenced by it.
1) The pollen grain of Brassica napus germinated best on the 40μthick medium of 60% yellow gelatin contained 10% sucrose, but the pollen grain plasmoptysed very much in the 100% relative humidity. The thicker the medium, the more plasmoptysed pollen grain decreased. 2) Even on the medium of optimum concentration the pollen grain plasmoptysed in the 100% R. H. of the moist chamber, but in lower humidity no pollen grain plasmoptysed and the highest rate of 98.5% germination was obtained in the optimum humidity. 3) The pollen tube was the longest, 2240μ, on the 30% lean gelatin medium. But the tube length was 1400μ on the 10% sucrose-60% gelatin which permitted the highest germination. The tube length did not always go together with germination ratio. 4) The water economy should exist between the pollen grain and the medium, as follows. When the thin layer of gelatin medium absorbed air moisture by the action of deliquescense and hydrature equilibrium, the moisture stay at its surface, the pollen grain sucking the water and swelling quickly. Then, the water gradually penetrates into the deeper part of the medium accompanying the decrease of excess moisture from the medium surface. Thus the water absorption of the pollen grain is controlled properly for germination.
Photosynthesis pattern relating to light intensity and the process of the differentiation in pattern have been pursued in natural phytoplankton community of lakes. 1. Phytoplankton growing in a lake can be classified into the sun and shade forms through the characteristics in photosynthesis-light curve. The typical sun form phytoplankton is usually obtained in the surface layer phytoplankton in early summer and autumn, and the phytoplankton taken from deeper layer acts as the shade form. During late summer and winter, all phytoplankton in a lake indicates the shade type photosynthesis. 2. The photosynthesis pattern differs with difference of species but the difference is rather slight under the optimal environmental condition for each species. Regional difference in photosynthesis pattern can be observed definitely. The phytoplankton acts as a sun form in enriched water of eutrophic lakes and a shade form in poor water of oligotrophic lakes. 3. The factors relating to the differentiation of photosynthesis pattern, i.e. light, temperature and nutrients, are ascertained experimentaly. However, the effect of past history of environmental factors on the photosynthesis pattern does not hold for a long period and the pattern rapidly transforms through the change of environmental factors. 4. The differentiation of photosynthesis pattern directly refers to the movement of water in lakes. During the circulation period, all phytoplankton in a photic layer show the sun-type photosynthesis pattern and with stagnating of water the photosynthesis pattern differentiates into the sun type in the surface phytoplankton and the shade one in the deep-layer phytoplankton.
An inductive dark period of 16 hours was divided into 4 phases consisting of 4hours each. 1) Light-sensitivity of these 4 phases was investigated. The first phase was most stable to the light, the light-stability of the 2nd, 4th and 3rd phases decreasing in the order mentioned. The first phase proceeded to some extent under daylight fluorescent light of 2000lux, but the 3rd phase did not proceed under light of 10lux. 2) Light-stability of the 1st phase was not influenced by the light-intensity preceding it. 3) Spectral sensitivity of the inductive dark process varied with the phase. During the 1st and 2nd phases, far-red radiant energy was more effective than red. During the 3rd and 4th phases, red was more effective than far-red. In the first phase, blue was less effective than violet, but the reverse was the case in the other three phases. In all phases, blue and violet were less effective than red or far-red.
1. The Carnoy's fluid and 45% acetic acid are good fixatives to fix the nuclear material of yeast cells. 2. The method in which the treatment with cell-wall lytic enzyme, the fixation with Carnoy's fluid, hydrolysis with 1 N-HCl at 60°and staining with aceto-carmine or Giemsa's staining are used subsequently is very effective to observe the nuclear material. 3. The solution of CdCl2 is effective to fix the spindle of the yeast-cell. 4. Carnoy's fluid, 45% acetic acid and Flemming's solution can fix the contents of the vacuole fairly well. 5. The nucleus changes to the spindle when the mitosis begins and the chromosomes appear in the spindle, overlapping the vacuole.
Pharbitis purpurea Voigt was cultured on Knop's solution whose iron was deficient in various degrees without inducing chlorosis in leaves. Three short-day treatments consisting of 8-hour light and 16-hour dark periods were given about 15 days after the germination, and flowering responses were observed. 1) When iron was deficient throughout the period of plant growth, the effect of short day treatment was decreased with decreasing iron concentration. 2) Iron deficiency preceding the short day treatment gave no influence on the flowering responses, but that during and/or following the short day treatment gave significant influences. The moderate deficiency of iron (5mg./l of FeCl3•6H2O) given during the short day treatment increased flowering response to some extent, but reduced when the same iron-level was continued after the short day treatment. 3) It was considered that the flower initiation was inhibited not by iron deficiency during the period before the short day treatments, but by the iron deficiency after the short day treatment. The moderate iron-deficiency during the short day treatment may accelerate the flowering response. 4) Plants were cultured under iron-deficient condition throughout the total period, and glucose was supplied before, during or after the short day treatment. The glucose promoted flowering response when supplied before or during the short day treatment, but inhibited when supplied after the short day treatment. A remarkable flower-promoting effect of the glucose was obtained under the moderate iron-deficient condition.
1) The seasonal variation in the amount of the zoospore of aquatic Phycomycetes was studied from October, 1957 to September, 1958 in Lake Shinseiko, Kanagawa Prefecture. The number of the zoospore increased both in spring and autumn, and decreased in summer and winter. 2) The vertical distribution of the zoospore varied with different seasons. There were two main types, i. e. the homogeneous distribution and the stratum one. The former appeared during the circulation period and the latter during the stagnation period. 3) Seven species were obtained from the lake. Saprolegnia monoica, S. diclina, Isoachlyaecocentrica, Dictyuchus sp. and Aphanomyces sp. were seen from autumn to early spring, and Achlya sp. was found mostly in summer. Pythium sp. was obtained through the year with the maximum in spring and autumn. 4) Aphanomyces sp. and Pythium sp. were distributed only in the surface layer during the stagnation period. During the circulation period, however, Aphanomyces sp. was distributed mostly in the bottom layer. 5) The zoospore production may be influenced not only by the water temperature, but also by the multiplication of periphytic bacteria. The optimum temperature for the zoospore formation in some species was as follows. Saprolegnia monoica 10-20°, Aphanomyces sp. 5-15°, Pythium sp. 5-30°
In this paper, purposes, methods and materials were described and a part of the results obtained in some species of annual and biennial dicotyledonous plants was preliminarily reported. Special studies in detail will appear in the future papers of this series. The primary and secondary branches were observed in genetic sequence from the lowest one towards the upper along the respective mother axis. After the observation on hundreds of branches, the cathodic prophylls on the branches of the same genetic number were added together. The results thus obtained in each species were expressed by the frequency curve of cathodic prophylls of its own. In the case of the primary branch, the frequency curves may be divided by their trend into three types, i.e. type A (Xanthium canadense Mill., Fig. 4, A), type B (Erigeron sumatrensis Retz., Fig. 4, B; Nigella damascena L., Brassica Napus L., Brassica Rapa L. var. laciniifolia Kitam.) and type C (Impatiens Balsamina L. Fig. 4, C1, C2; Kochia Scoparia Schrad., Fig. 4, C3; Amaranthus ascenders Loisel.). In the case of the well-developed secondary branch, the frequency curve of cathodic prophylls is fundamentally similar in each species to that of the primary branch, but it is somewhat simpler. In every species the cathodic prophylls on the branches situated at the basal and terminal parts of a main axis and of a primary branch axis show characteristic local variations of frequency, different from the general trend of the frequency curve. It was preliminarily interpreted that these basal and terminal variations have resulted from some factors such as the special phyllotaxis, the plastochrone change, etc., characteristic to the basal and terminal parts of an axis. Analytical studies on the basal and terminal effects will give some suggestions upon the mechanism which determines the anodic or cathodic positions of prophylls.
1. At the first nuclear division in the zoosporangium of Undaria undariaides (Yendo) Okamura, synapsis stage and diakinesis are observed. Therefore, the first and second nuclear divisions in the zoosporangium are meiosis. 2. After meiosis, three successive mitoses take place to form 32 free nuclei. Consequently 32 haploid zoospores are contained in a zoosporangium. 3. The haploid chromosome number in the present species is about 30. 4. Both the centrosome and the aster are not observed. The spindle is delicate. 5. The nucleolus disappears at late diakinesis.
The somatic chromosome number of Houttuynia cordata Thunb. is 96. At the first metaphase in P. M. C., 48 bivalents tightly paired are observed. Some bivalents show secondary association. In a few cells, chromatid bridges are seen at anaphase. Abnormal tetrads with different number and shape of microsporocytes are often observed.