Two strains of TMV, TMV-C and Wasabi strain (W) isolated from crucifer plant in Japan contained 2 distinct amino acids, viz. histidine and methionine in their coat proteins. The amino acid compositions of TMV-C and W were similar to that of Holmes' ribgrass strain (HR). The C-terminal amino acid of TMV-C protein was threonine, but no free amino acid was liberated from W protein by the treatment with carboxypeptidase A and B. A Japanese tomato strain, TMV-L had the amino acid composition similar to Y-TAMV (yellow-tomato atypical mosaic virus) containing methionine. In polyacrylamide gel electrophoresis at pH 3.8 in 8M urea the protein of TMV-C showed almost the same mobility as those of HR and Lychnis strain (Ly), while W protein showed a higher mobility and TMV-L protein a lower mobility. The proteins of 3 ordinary strains, OM, O, and vulgare showed almost the same mobility as that of W protein. HR, Ly, and TMV-C showed the same sensitivity to inactivation by UV irradiation, and was about 3 times as sensitive as OM, while W was about 4 times as sensitive as OM. 06 and a tobacco form of cowpea mosaic virus obtained by inoculating Samsun tobacco with the bean-form of this virus were almost as sensitive as vulgare, and TMV-L and bean-form of cowpea mosaic virus were about 1.5 times as sensitive as OM. From the results mentioned above, it is reasonable to include HR, Ly, and TMV-C in the same group of TMV strain represented by HR, while W was not determined to which group it belongs, though its amino acid composition was similar to HR.

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Washed mycelia of Fusarium oxysporum f. raphani seeded in mineral salt solution produced chlamydospores within 24 to 48 hours and the number increased gradually. Initial chlamydospore formation delayed slightly in the mineral salt solution supplemented with 0.1% glucose, but the number increased rapidly thereafter. In 144 hours, production of chlamydospores reached stationary phase and the number formed in water remained about 60% as many as that in the mineral salt solution. Mycelial growth was always observed prior to chlamydospore formation in these media. Glucose was shown to promote mycelial growth and repress chlamydospore formation. Nevertheless, at the stationary phase the number of chlamydospores was increased proportionally to the amount of glucose added into the medium and of the mycelia seeded. Production of chlamydospores in the medium was repressed in the pH below 4 or above 8, and also repressed in CO₂ and in N₂ atmosphere. Chlamydospore formation was best at 28°C as well as mycelial growth, but in higher temperatures it was more sensitive than mycelial growth. The mineral salt solution lacking one of the elements repressed the production of chlamydospores moderately or completely as a result of repression of the mycelial growth.
From these results, it is suggested that the fungus does mycelial growth as much as possible, utilizing the carbon source in the medium and in the mycelium itself, followed by chlamydospore formation from the mycelium at the definite rate.

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Hybrid virus particles were reconstituted by RNA and protein extracted from tobacco mosaic virus crucifer strain (C) and ordinary strain (OM), or C and Bean strain (B). The reconstituted viral yield of the combination ‘C-RNA+OM-protein’ was markedly lower than those of the other combinations. According to sucrose density gradient centrifugation of the reconstituted substances prepared from the combination ‘C-RNA+OM-protein’, the virus particles of 300mμ in length were smaller in number. On the other hand, C-protein reacted sufficiently with OM-RNA or B-RNA, and they formed efficiently the complete virus particles. The reconstituted virus ‘OM-RNA+C-protein’ revealed similar specific infectivity to the reconstituted virus ‘OM-RNA+OM-protein’. Specific infectivity of the reconstituted viruses was almost equal to that of the standard virus (intact OM) on the primary leaves of Phaseolus vulgaris whereas the former was lower than the latter on the leaves of Nicotiana glutinosa. The reconstituted viruses were more sensitive to RNase than the standard virus.

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The present paper deals with experiments on the effect of light on lesion development in cucumber downy mildew, caused by Pseudoperonospora cubensis (Berk. et Curt.) Rostow.
1. Infected cucumber leaves kept in darkness for 5 to 8 days after inoculation showed a marked decrease in lesion development. Dark treatment for 2 days befor inoculation, however, gave no effect to lesion development.
2. As the period of darkness during which infected leaves were kept after inoculation was prolonged, the lesion development was proportionately checked. Especially, the lesion development was remarkably suppressed when kept in darkness for 3 or more days after inoculation.
3. Lesion development was affected by the light intensity of from 0 to 0.35cal/cm²/min, provided by mercury lamps, when exposed after inoculation. Lesion area decreased with the decrease of light intensity. The rate of decrease was more conspicuous in the light intensity range below the light compensation point of cucumber leaf, 0.05cal/cm²/min.
4. Effect of photosynthetic inhibitors on lesion development was examined. Solutions of photosynthetic inhibitors linuron (3-(3, 4-dichlorophenyl)-1-methoxy-1-methylurea) and simazine (2-chloro-4, 6-bisethylamino-1, 3, 5-triazine) were sprayed onto the upper surface of infected leaves 2 days after inoculation, or of healthy leaves.
By the application of linuron, conspicuous decrease in lesion area in infected leaf and also conspicuous reduction of photosynthesis in healthy leaf were observed. As the concentration of linuron was increased from 10 to 50ppm, the inhibition of lesion development and of photosynthesis increased, the inhibition being more pronounced at 30ppm and above. Linuron showed no effect on conidial germination at the concentration of 30ppm. Simazine inhibited neither lesion development in infected leaf nor photosynthesis in healthy leaf.
From these results it was concluded that the lesion development in cucumber downy mildew is closely dependent on the photosynthesis of the host plant.

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Changes of isozymes and soluble proteins in tobacco leaf inoculated with cucumber mosaic virus (ordinary strain) are reported. Isozymes and soluble proteins from tobacco leaf at the 4th hr's and 5th day's infection were separated by polyacrylamide gel electrophoresis.
These changes were inconspicuous at the 4th hr's infection, but clearly demonstrated at the 5th day. In infected leaf but not in healthy leaf, proteins, having high molecular weight, were separated on 4.75% gel, remaining their origin unsolved. Peroxidase isozymes pattern did not change by infection, but a few bands of them were activated by the prolonged times of infection. The same tendency was observed by ageing in healthy control leaf. Similar results were obtained in polyphenoloxidase. Total activities of peroxidase and polyphenoloxidase in infected leaf were higher than those in the control. The number of glutamate dehydrogenase isozymes and isocitrate and isocitrate dehydrogenase isozymes decreased by infection. However, activities of glutamate dehydrogenase isozymes in infected leaf were higher than those in the control, and this tendency was reversed in the case of isocitrate dehydrogenase isozymes. Generally, activities of glucose-6-phosphate dehydrogenase isozymes became weak at the 5th day's infection, although some bands showed stronger reaction in infected leaf than in the control. 6-Phosphogluconate dehydrogenase isozymes showed the same tendency as glucose-6-phosphate dehydrogenase isozymes, nevertheless a new band appeared both in infected and control leaf by ageing. The number of acid phosphatase isozymes decreased by infection, but their activities in infected leaf were slightly higher than in the control. Malate dehydrogenase isozymes pattern did not change, but their activities lowered by infection. In infected leaf one band of them remained comparatively high activity even at the 5th day.
These results seem to indicate that changes of the isozymes herein reported are caused by the abnormally physiological state of host plants, including ageing, which may be induced by infection.

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