In the previous paper, it was suggested that the browning phenomena of lesions might take part in the resistance of leaf tissues of rice to the blast disease, caused by Piricularia oryzae.
This paper deals with the constituent of rice Plant which may probably give rise to the brown coloration. Results of analysis of amino scids showed that tryptophane and tyrosine could not be copsidered as the main causes of the brown coloration, despite granules turning red with Ehrlich's aldehyde reagent were usually observed in affected cells of assimilating tissue, suggesting Probably the presence of some indole derivatives. The cell membranes of vascular bundle collenchym, and epidermis turn red to orange with diazo reagent. By means of staining methods using Liebermann's nitroso reaction or Hopfner's reaction, phloroglucinol-HCI, benzidine-HCI, Payen's reaction, ammonium solution, FeCl₃ solution, and conc. H₂SO₄ revealed that these membranes reacted quite similar to chlorogenic acid. In addition chlorogenic acid was detected in the crude extract of leave by means of paper chromatography.
Chlorogenic acid apPears to exist usually in a form not free but combined with a certain constituent of cell membrane. The presence of chlorogenic acid in the cell membrane may account for the browing of cell membranes of the affected tissues which usually precedes the browning of cell content. Moreover, results of further observations suggest that there exists a possibility that chlorogenic acid is produced and accumulates in affected cells and causes the browning of cell contents.

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The Lugol-Giemsa method described by Bald (1949), trypan-blue method by McWhorter (1941), and-pyronin-methyl green stain were tested for selective staining of the intracellula inclusions in potato and other Solanaceous plants produced by the X-and Y-virues of the potato. The tissue observed was integumentary, consisting of epidermal peelings from disaesed leaves and petioles. The Giemsa method brought about the best results, staining the viroplasm and the nucleolus violet (not purple) and the nucleus light blue; while the pyronin-methyl green stain failed to provide any differentiation, staining both the healthy and the diseased plasm red. The trypan-blue staining was found to be unsatisfactory.
Potato virus X (PXV)-Deeply staining material, presumably virus, was found to extend around the cells in potato, tobacco and tomato plants infected with the mottle strain of virus X (Fig. 3, C, D, G; and Fig. 1 in Plate). A more disperse material, also staining violet with Giemsa, was detected in the cytoplasm or near the nuclei (Fig. 3, A, B, E, H, I), which, in some cases, entirely embedded the whole cell content (Fig. 3, F). The apparently healthy potato carieties, carrying virus X, contained the same inclusions in the later stage of growth. The needle-like crystalline inclusions, stained with Giemsa and dissolved in acid and alkali, were also observed in the same varieties (Fig. 1).
Potato virus Y (PYV)-A small granular inclusions were present in potato, tabacco and tomato plants infected with the ordinary strain of virus Y (Fig. 3, J, K, O; and Fig. 2-4 in Plate). The deeply staining and the disperse materials which somewhat resemble those caused by virus X, were also detected in the same Plants (Fig. 3, L-N). Potato variety, Iwate No. 4, which carries virus Y, has contained the same inclusions. The intranuclear crystalline inclusions showing the proteinaceous reactions were found in fall in tobacco plants grown in the dry soils (Fig. 2).
Potato virus X plus virus Y (PXV+PYV)-In this case, the PXV-type inclusios alone or associated with the PYV-type inclusions were observed in one cell in potato and tobacco plants (Fig. 3, P, Q; and Fig. 5-7 in Plate). On the other hand, a large vacuolated inclusions (X+Y type) were also prevalent, especially in potato plants (Fig. 3, R-U; and Fig. 8 in Plate). The chemical nature of the inclusions-Results obtained with the materials infected with virus Y are now presented below. The Millon reaction and the xanthoprotei test provided evidence of protein in the inclusions. They were also positive to Nadi and benzidin reactions (but not inhibited by KCN). They were not stained in the Feulgen reaction. When the materials were fixed with Regaud's solution or treated with hot (60°C) hydrochloric acid (both the treament to remove ribonucleic acid), the inclusions were not stained with thionin, toluidin blue, methylene blue, and oresyl blue. The materials pretreated with tri chloracetic acid (90°C, 15min.), did not absorb any dyes tested except the trypan-blue. These results seem to suggest the presence of ribonucleic, acid in the inclusions. the reason why the Nadi and benzidi reactions were positive in the inclusions remains unknown, but the writers should like to consider that the non-crystalline inclusions are composed of both viruses and some of the host materials. The hest materials, like mitochondria and so on, have been demonstrated to react to Nadi solution when the host cells resist to the infection by viruses or fungi. It seems reasonable, therefore, to conclude that the inclusions, especially non-crystalline, may be the product of the interaction of viruses and host materials, though the crystalline inclusions within the nuclei have proved to be a pure nucleoprotein.

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1. In the present paper the writer described the results of the experiments on the relation of silicic acid supply on soil to the disease outbreak in rice plants.
2. The application of silicic acid on soil increases the resistance to blast disease on pedicels of spikes of rice plants and the application of silica with boric acid er copper sulphate decreases effectiveness of silica given. Single supply of boric acid or copper sulphate on soil may cause a little suppression to the outbreak of rice blast disease.
3. The relation of the supply of silicic acid, with boric acid, or copper sulphate on soil to the outbreak of Helrminthosporium-blight on leaves is entirely similar to that of blast disease. The silicification of epidermal cell walls in adult leaves increased remarkably with the supply of silicic acid on soil. Single application of boric acid on soil resulted in a little increase of the silicification, but copper sulphate supply has the tendency to inhibit the silicification of leaves.

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The nutritional physiology of the rice blast fungus, Piricularia oryzae has been studied with special reference to the growth factors. The constitution of the standard mediurn used was as follows: NaNO₃ 2.0g., KH₂PO₄ 0.5g., K₂HPO₄ 0.5g., MgSO₄ 0.5g., CaCl₂ 0.1g., Sucrose 20g., Biotin 5μg., Thiamine hydrochloride 500μg., MoO₄Na₂·2H₂O 0.05mg., Na₂B₄O₇·10H₂O 0.1mg., FeCl₃ 0.4mg., CuSO₄·5H₃O 0.4mg., MnSO₄·7H₂O 7.5mg., ZnSO₄·7H₂O 7.5mg., and a litre of distilled water. The followîngs were shown from the results of the study:
1. Thiamine or both of its two components, pyrimidine and thiazole are essential for the growth of the fungus. If one of the components is absent in the culture solution, the fungus can not grow in it.
2. The minimum requirement of biotin was abaut 0.004μg., and that of thiamine hydrochloride was about 0.2μg. in 10ml of culture solution.
3. Some of sugars and higher alcohols were tested as the carbon source. The results indicated that sugars were preferable to the higher alcohols for the growth of the fungus in general. Sorbose and inosit were not utilized as the carbon source.
4. Ammonium sulfate, sodium gluamate, asparagine and sodium nitrate were tested as the nitrogen sonrce. In the media containing equivalent amount of nitrogen, the order of rate of growth was found to be: Ammonium sulfate> Sodium glutamate> Asparagine> Sodium nitrate. Among the amino acids present in the rice plant, aspartic and glutamic acids were the most suitable, whereas, tyrosine and phenylalanine were inferior to the other amino acids. When small amoun of asparagine or glutamine was added to the culture solution, the growth of the fungus was somewhat promoted. Aspartic and glutamic acids offered the similar but less effect as above. Some of the organic acids such as malic, succinic, citrie, and tartaric acids, were effective for the promotion of the fungus growth, and especially the ammonium salts of them were stimulative.
5. Amino acids of the mycelial mat developed in culture solution containing inorganic nitrogen source such as nitrate or ammonium salt, were analyzed by the paper chromatography. The following amino acids are detected by the analyses Aspartic acid, glutamic acid, glycine, alanine, valine, leucines (leucine and or isoleucine), lysiae, arginine, histidine, threonine, proline, tyrosine, phenylalanine and methionine.
6. The nutritional requirements of about fifty isolstes of this fungus were compared. There were no differences among them, however, as for the growth factor requirements. By the irradiation of the ultraviolet ray to the spore, a mutant appeared which required adenine in addition to biotin and thiamine as growth factors. This mutant is similar to the mother isolate in spore formation and spore size, but the colour of the mycelia on rice straw decoction agar is slightly deeper than that of the mother isolate. This mutant remained pathogenic to rice plant.

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Carbon sources of Piricularia oryzae were studied, using synthetic culture solutions containing biotin and vitamin B₁ that have been. recently shown to be indispensable for Piricularia oryzae. Carbon sources studied are the following-sugars: viz., glucose, fructose, galactose, sucrose, lactose, maltose; polysaccharides: viz., soluble starch, inulin; higher alcohols: viz., glycerine, mannit; and organic acids: viz., formic acid, acetic acid, oxalic acid, succinic acid, lactic acid, citric acid.
According to the here-described experiments, sucrose and maltose are the most excellent carbon sources for the present fungus. Glucose, inulin and mannit follow them in succesion in relation to the carbon nutrition. Carbonic acids are generally improper as carbon source of the present fungus, but pretty good mycelial development is observed in solutions containing succinic acid and citric acid, which are included in Krebs' T.C.A. cycle. This fact suggests the connection of Piricularia oryzae's metabolism with the T.C.A. cycle.
Carbon sources, on which mycelial development is clearly observed, are enumerated in the order of their nutritiousness as follows: 1. maltose, 2. sucrose, 3. glucose, 4. inulin, 5. mannit, 6. succinic acid, 7. fructose, 8. soluble starch, 9. lactose, 10. citric acid, and 11. galactose.

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During the past two years, while the author has been intending to make a list of the parasitic fungi occurring on useful plants in the Tohoku District, several interesting fungi, new to science or newly added to the mycological flora of Japan, have been found among the materials collected in this district.
In the present paper some of them are enumerated and the remains shall be published in near future after finishing their identification.
The writer wishes to express his hearty thanks to the late Dr. K. Togashi, Yokohama National University for his valuable suggestions and kind guidance, and grateful acknowledgments are due to Prof. S. Akai, Prof. H. Asuyama and Prof. M. Nagai for the permission of free useing literatures. He is also indebted to Mr. S. Katsuki, Agr. Improv. Sect. Fukuoka Pref. Gov't. for his kind assistance in identification.

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In order to research the influence of cephalothecin upon the secretion of some carbohydrases by the blast fungus, Piricularia oryzae CAV. cultural experiments were carried out using Tochinai and Nakano's synthetic nutrient solution, with addition of Biotin (15-20mr/1cc.) and vitamin B₁ (15-20γ/1cc.).
In the solutions. cephalothecin was added at strengths of 1: 5-164. half of the lots was provided with one of the carbohydrates, including sucrose. maltose, soluble starch and cellulose and another half lacked. After 10-days culture at 25°C, determinations of reducing sugars were made upon the cultured solutions.
When the fungus was cultured in cephalothecin solutions with carbohydates, there were increase in dry weight of mycelial mat, and decrease in weight of non-reducing sugars, as against the solutions without any carbohydrate. The differences are shown as M and S respectively. The ratio S: M is temporarily called as the relative secretion value.
When sucrose is supplied as the carbon source, the ratio S: M is highest at the concentration of 1:20 cephalothecin (of. table 5). Such secretions as of sucrase by the fungus may be called sucrase-type. Maltase also belongs to this type.
In the solution containing soluble starch, the value is maximum at the concentration of 1:40 cephalothecin. These phases, which are quite different from those in sucrase-type, may be named amylase-type.
No cellulose was utilized by the fungus in the presence of cephalothecin. This, together with other carbohydrates-emulsin, inulinase, lactase, mannase, pectinase and xylanase-may be included in cellulase-type.
The relative secretion value (S:M) shows the amount of the carbohydrate consumed by the fungus to increase 1mg. of the mycelium in dry weight. Accordingly, for the consumption of 1 mg. of sucrose or soluble starch, the increase in dry weight of mycelium is to be far less in 1:20 or 1:40 solution of cephalothecin than either in 1:80-160 or in the check solution, In 1:5-10 solutions, the growth of the fungus is extremely poor. Thus, the phases of S:M suggests certain connection between the fungus's secretion of carbahydrases under the influence of cephalothecin and the resistance to blast disease of the rice plant treated with cephalothecin.

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The isolation of the pathogene was performed in July of 1952. In the coursh of this work, we noticed several microbes antagonistic to the parasites and selected five lines (A, B, C, D and E) which showed higher antagonistic activities. Theiractivities were higher in order of C, D, A, B and E.

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The present paper reported the results of experiments on the varietal resistance of eggplants to the bacterial wilt disease caused by Pseudomonas solanacearum, using two varieties, Daisen Maru No. 2 (susceptible) and Durable Shinkuro (resistant). From the morphological observations, the writer found cicatrice around the affected parts of eggplants. There were no essential differences, in these morphological barriers between the two varieties used.
No definite bacteriostatic effect in the exuded juice from the surface of both plants or in the expressed juice of plant was observed. The growth of the bacteria on the surface of plant, however, was definitely suppressed in the resistant variety.
The writer also observed a change in the population of the pathogenic bacteria within leaf tissues of both plants after the artificial injection. After forty eight hours, the writer found a large difference in the population of bacteria in the two plant tissues, showing the acceleration in Daisen Maru and the inhibition in Durable Shinkuro.
The chromatographic separation of the expressed juice was also performed. The treated papers were cut into three parts and dried. They were called C, B, and A from the top, respectively. A₁, B₁, C₁ belong to Daisen Maru, and A₂, B₂, C₂ to Durable Shinkuro. The writer extracted the substances of every part of the papers into distilled water with the following eight combinations: A₁B₁C₁, A₂B₁C₁, A₁B₂C₁, A₁B₁C₂, A₂B₂C₂, A₁B₂C₂, A₂B₁C₂, A₂B₂C₁. Thus the suppressive effect of these extracts upon bacterial growth was examined. From the results of these experiments, the writer confirmed the most strongest suppressive effect in C fraction of Shinkuro juice.

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1.To ascertain the effect of mixed infection by white tip nematodes and stem-rot fungus potted rice plants(Variety Asahi) were inoculated with husks of the nematode diseased grains or stemrot sclerotia.
2.The severity of stem-rot infection of the plants mixed inoculated with nematode and the stemrote sclerotia at the same time was lower than the plants inoculated only with the stem-rot fungus.
3. Both ear weight and 1000 unhulled-graing weight of rice decreased in the following order of plants infected with stem-rot fungus, with nematode, and mixed infected with both causal organisms.

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1. The oldest leaves of the barley seedlings preserve their faculty of germicidal action in the drops which were inoculated with Fusarium solani on the injured parts for one day and lost it 3 days after. The youngest leaves preserve this faculty of germicidal action for more than 3 days.
2. It was suggested that the germicidal action in the drops is unstable, because it was inactivated by keeping in a moist chamber for one day, by heating for 10 minutes at 60°C and 100°C or by drying at room temperature (18°C).

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[in Japanese]

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