1. This paper deals with the results of the writer's experiments on the infection of the rice plant by Piricularia Oryzae Br. et Cav. 2. The results of the inoculation experiments showed that the fungus is able to infect the rice seeds before, at and after the flowering period of the plant. However, the diseased signs did not necessarily appear on their glumes. Regardless of the difference in the inoculation period, the slightly infected seeds matured either normally or sometimes abnormally, while in the case of severe infection the kernels failed to develop completely, the seeds being represented by the glumes alone. 3. The results of writer's experiments on the relation of the inoculation time to the infection of the kernels indicated that the rate of the infection at the different times tested seems to be almost uniform. 4. The absence of the diseased signs on the glumes of the seeds, which were inoculated with Piricularia Oryzae before, at and after the flowering period, can not be taken as a conclusive evidence for the health of the kernels, because some of the seeds with apparently healthy glumes contained often the diseased kernels. 5. The seeds and the kernels showing the diseased appearance from the inoculated lots weighed sometimes almost as much as those having the healthy appearance from the same lots or those of the controls. 6. The fungus having the same characters as those of the inoculum was not only reisolated from the kernels of the diseased appearance, but also from those of the healthy appearance from the inoculated lots. However, the fungus was not obtained from any kernel of those in the controls. 7. The microscopical examinations of the seeds inoculated before, at and after the flowering period showed without exception the presence of the fungus hyphae ramifying in the tissues of the embryo, endosperm, bran layers and of the glumes or sometimes between the glume and the kernel. The existence of the fungus conidial between the glume and the kernel was also proved. This facts show that the fungus is able to penetrate into every part of the seed. 8. The kernels from the seeds inoculated at the different times were sterilized by a special method and sowed on Sachs' nutrient agar in the Erlenmeyer flasks. The young seedlings grown from those seeds were soon killed by the internal fungus, showing the symptoms of the blight or the rot. Judging from the above fact, the fungus remaining alive within the seeds seems to become active with the germination of the seeds and cause the first infection of the disease under a certain condition. 9. Regardless of the difference of the inoculation time, any remarkable discrepancy in the percentage of germination was not recognized, not only between the kernels with the diseased signs and those of the healthy appearance from the inoculated lots, but also between those from the inoculated lots and the controls. 10. The phenomenon of the rice blast disease under consideration is different from the true flower infection of the loose smut of wheat and barley in the fact that the first infection caused by the fungus existing within the seeds appears on the seedlings resulting in their blight or rot, instead on the seeds at the flowering period. It also differs from Arlandt's “Paleal- und Anthere infektion” or Zade's “Blütenkeimlingsinfektion” of the loose smut of oats where the fungus hyphae is found in the seed coat, parenchyma of the glume and shrivelled anthers whereas in this case the fungus hyphae exists within the tissues of the endosperm and embryo as in the case of the true flower infection.
This paper deals with a bacterial blight of chestnut and its causal organism. The disease is mostly conspicuous in buds and young shoots though also occurs on the leaves, veins, petioles and bracteal leaves, the last being usually attacked at first. The sign of the disease in the early stage is water-soaked spots on the leaves and young shoots in which the cortical parenchyma is destroyed, forming the bacterial cavities and resulting in brown cracks. Leaves attacked when young become distorted and leaves of infected buds shrivel and die. White and yellow bacteria are isolated from the diseased lesions, of which the former is proved to be pathogenic to chestnut and found associated with the latter, usually at a later stage of the disease. The morphological, cultural and physiological characters of the causal organism has been studied and Bacterium Castaneae n. sp. is proposed for the organism. The technical description of Bacterium Castaneae n. sp. is as follows: A short rod, 1.0-1.8μ long by 0.8-1.2μ wide, motile by one to five polar flagella; singly or in pairs; no spores; no capsules; Gram-negative; facultative anaerobic; beef agar colonies white, round, slightly undulate and viscid; bouillon clouds without pellicle; potato decoction agar colonies white, radiately rugose; gelatin not liquefied; diastatic action absent; milk peptonized without coagulation; indol and hydrogen sulphide not produced; nitrate and methylene blue reduced; acid from dextrose, saccharose and glycerine without gas, neither acid nor gas produced from lactose, no gas from maltose and potassium nitrate; optimum temperature 25°-27°C., minimum below 3°C., maximum 35°C., thermal death point 50°-51°C.; parasitic on chestnut causing leaf sports and brown cracked lesions on the veins, petioles and shoots and destroying the buds; type locality Kasuya, Fukuoka, Japan.