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.
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.