The difference in so-called host range between the parasitic species and the saprophytic ones of sooty mould fungi was examined with Formosan specimens of about 170 species belonging to the Meliolaceae, the Microthyriaceae and the Capnodiaceae. The host range of the parasitic species belonging to Meliola, Meliolina, Irene, Irenopsis, Irenina, Amazonia and Balladyna of the Meliolaceae, and to Asterina, Parasterina, Lembosia and Morenoella of the Microthyriaceae was limited to several species in the same genus or in the same family. Among the species of the host plants there was such specific relationship as is found in the host plants of the parasites of other pathogenic fungi.
As shown in the tables 2∼5, the so-called host range of the saprophytic species belonging to Capnodium, Neocapnodium, Capnophaeum, Scorias, Chaetoscorias, Hypocapnodium, Aithaloderma, Limacinia, Chaetothyrium, Phaeosaccardinula, and Triposporiopsis of the Capnodiaceae was markedly varied; i. e. these host plants of Phaeosaccardinula javanica (Zimm.) Yam., Neocapnodium Tanakae (Shir. et Hara) Yam., Triposporiopsis spinigera (v Höhn.) Yam., Aithaloderma clavatisporum Syd. Hypocapnodium setosum (Zimm.) Speg., Scorias cylindrica Yam. and Capnodium Walteri Sacc. were respectively 48 species in 29 families, 48 species in 18 families, 38 species in 17 families, 13 species in 11 families, 9 species in 6 families, 3 species in 3 families and 2 species in 2 families. No specific relationship existed among the species of the host plants.
Since the saprophytic sooty mould fungi can well grow in the honeydew on any kind of plants when the pycnospores, conidia or mycelial fragments of the moulds are disseminated on the honeydew of various insects such as ants, flies, wasps and bees, the host range of the saprophytic species was considered to be determined by mean of the deposit of the honeydew and the extent of dissemination of the moulds.

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1. When the conidia of barley mildew, Erysiphe graminis hordei, germinated on the epidermal strips of onion scales, which were deprived of their soluble content by immersing in alcohol for a long time and by subsequent washing with running water, the germ tubes remained alive for a week. While on a living barley leaf of comparatively resistant varieties, penetration hypha was usually enveloped by a big callus during the process of penetration, and the germ tubes were killed within one or two days after inoculation. It is suggested that the germ tube is presumably killed by a certain substance or substances produced near the penetrated point in the barley cell, and not by the mechanical impediment of the callus. The degree of callus formation varies with the variety of barley, growth stage, rate of application of nitrogen and silica, etc.
2. After a few days after inoculation, it was occasionally observed that both living and dead haustoria existed in the same and one living epidermal cell. This fact indicates that when one or some haustoria die, the host cell or the other haustoria in the same cell will not always be injured immediately.
3. Long epidermal cells under the old pustule are usually colonized by so many haustoria, often reaching 70 or 80 in number. Among many living haustoria in such a host cell, which is evidently alive, dead ones are often observable.
4. When a detached, diseased barley leaf is kept in a moist Petri dish, the leaf turns yellow and ultimately dies except the pustule bearing part. The epidermal cells in such area left alive, surrounded by dead tissues on all sides, are nearly dead or apparently dead and yet some of them contain living haustoria. It may be said from these observations that the haustoria, at least a part of them, in the dying cell do not precede in death to the host cell.
5. The barley mildew developed a longer hypha without haustorial formation, on the bleached onion epidermis, floated on glucose solution or on a culture solution containig yeast-extract, than on the substratum floated on water.
6. Primordial haustoria, just beginning to develop finger-like processes, were formed, though very rarely, in the epidermal cells of buckwheat, but no hyphal development from the germ tubes was observed.

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The root-rot of sugar beets caused by Pellicularia filamentosa (Pat.) Rogers (Rhizoctonia solani) is prevalent in some regions of Hokkaido. The occurrence of the disease and the amount of the pathogens in soil were observed during the growing season of the host plants in the farm where has been observed the severe annual occurrence of the dry-rot canker or crown-rot of sugar beets. The damping-off of seedlings caused by the same pathogen was severe in May and the root-rot or crown-rot in matured plants appeared after the last decade of July, but few rotting symptom of the roots could be observed during the intermediate seasons between these severe outbreaks of the root disease. The increasing tendency of the density of pathogens in soil was almost parallel to the prevalence of the disease.

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In August, 1954, a virulent outbreak of blight in the field of Kennebec potatoes at Sugadaira Foundation Seed Potato Farm, Nagano Pref., was reported and blighted leaves were sent to our laboratory for the identification of race of the fungus. In the same year several leaf lesions of late blight were also found in the field of resistant hybrid varieties in Kotoni, Sapporo.
Isolates from these lesions have been proved different from the common field race through the artificial inoculation test made on several blight resistant varieties derived from S. demissum. There have been recognized two races besides common one: H₃ and H₇ isolates which attack Kennebec and related varieties and H₂ and others which infect resistant, hybrid 48005-83. The formers do not cause lesion on the leaves of 48005-83 while the latters do not attack Kennebec.
This is the first record of new races of Phytophthora infestans in Japan.

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Conidiophores of the brown spot fungus of rice plant are produced on the “disintegrated zone” ofa diseased spot usually through stomata, when the affected leaves are still vigorous. Zone of the conidial formation enlarges gradually with the weakening of the leaves, and when the leaves die, it becomes to extend widely beyond the border of a diseased spot.
The formation of conidia has been observed by use of a modified TOYOTA and SUZUKI'S cell. The conidiophores appear first after about 5-14 hours and grow very slowly in the atmosphere of 18-26°C. in temperature and nearly saturated moisture. The cells of the conidiophores are at first homogeneous and hyaline, then they turn granular and dark from base. A conidium starts as a sharp protrusion at the apex of a conidiophore (fig. 3) and develops first into a tiny hyaline sphere. It turns to egg-shape, then to cylindric, and finally tapers slightly at its apex, in the course of growing to a characteristic shape and size. In succession with this, there appears septation and coloration of the conidia, and granulation of the cell contents (figs. 5-13). At the ripening of the conidium, the conidiophore begins to branch laterally at the directly beneath the conidial attachment (figs. 14-15). The branch grows vigorously and the conidium inclines sharply becoming as if it was lateral (figs. 16-17). After that, the second condium is produced in the same manner; and so on to the following ones.

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(1) Recently it has been shown that some plant pathogenic fungi require growth factors for their normal development. The present paper deals with the results of experimental studies on the effects of thiamine and the nitrogen as well as the carbon sources of Stagonospora carpathica Baeum., the causal fungus of the brown spot of broad bean.
(2) In the cultural experiment using the modified Czapek-Dox solution, it has been shown clearly that the present fungus grows easily in the case of vitamin-free, while Ceratostomella fimbriata does not grow in the medium lacking thiamine. Judging from this fact thiamine is recognized to be the dispensable growth-factor for the present fungus.
(3) According to the results of the present experiment, both nitrate and nitrite seem to be good sources of nitrogen for the growth of Stagonospora carpathica BAEUM. Ammonium salts such as ammonium chloride or ammonium sulfate are worthless as nitrogen source for the present fungus, probably because of the dropping in pH value of the medium used, while the salts such as ammonium oxalate or ammonium citrate give the good result for its growth. It is, however, unknown whether the oxalate or citrate acts as carbon source for the present fungus.
(4) The various amino-acids and amides differ in value from each other as nitrogen source for the growth of this fungus. As nitrogen source, tyrosine, glycocoll and asparagine are of use better, but worse in leucine and urea than nitrate. It seems to be doubtless that cystine and thiourea are inadequate nitrogen sources for this fungus.
(5) Judging from the results of the writer's experiment on the present fungus, fructose, arabinose and xylose are most excellent as carbon sources, being followed by glucose, mannose, galactose, sucrose, maltose and starch. As carbon sources lactose and mannitol are not advisable to use and glycerol is not proper for the present fungus.

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In the present paper, the results of a study on the nitrogen metabolism of the causal fungi of stem rot of rice plant, Leptosphaeria salvinii Catt. and Helminthosporium sigmoideum Cav. irregulare Cralley et Tullis. Both fungi were cultured in liquid media at 25°C for 3 weeks. The nutrient solutions contained one of the following substances respectively, as a nitrogen source: KNO₃, (NH₄)₂SO₄, (NH₄)₂HPO₃, NH₄NO₃, NaNO₂, urea and peptone. Decoction of straws and leaves of rice plant was added to the nutrient solution at a rate of 10%, as growth promoting substance.
Both fungi could not utilize NO₂-N, but absorb NH₃-N, NO₃-N, urea and peptone. Growth of the fungi was checked by NO₂-N. Difference in growth between the two fungi·was observed according to the kinds of nitrogen source. Leptosphaeria-fungus could grow better than Helminthosporium-fungus in the presence of (NH₄)₂SO₄, NH₄NO₃ and peptone, while Helminthosporium preferred (NH₄)₂HPO₄. The two fungi grew vigorously in the presence of nitrogenous substances which have not decreased the pH of the nutrient solution. Above all, peptone gave the best growth of them. When NH₃-N and NO₃-N co-exit, both fungi absorb NH₃-N selectively and quickly, and absorb NO₃-N later. Helminthosporium-fungus begins to absorb and utilize NO₃-N earlier than Leptosphaeria-fungus.

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1. The present report deals with the production as well as the isolation of a fungistatic substance, which was obtained from the culture filtrates of Gloeosporium Olivarum Alm. on media containing 2, 4-D Na salt.
2. When the acidified filtrates (pH 2.5) were shaked with ether and then with 4% NaOH, a brown oil was obtained in partly purified form after evaporation of ether. The growth of causal fungus was completely inhibited at the dilution of 1:5, 000 by this substance, of which activity was stable 130°C for at least 3 hours and not inactivated at a pH range between 4.0 and 11.2.
3. The inhibitory activity of 2, 4-D does not depend on its direct effect against the pathogen but mainly on this fungistatic product induced by addition of 2, 4-D.
4. The material toxic to the pathogen was produced most abundantly at 0.04% of 2, 4-D. On media supplied with 2, 4-D the fungal growth ceased within about twelve days of culture in spite of nonexhaustion of nutrients, however the production of the toxic material yet continued during the successive culture.
5. The yield was also maximum on a Richards's medium, of which components sodium nitrate was substituted by ammonium tartarate. The cause would probably be attributed to the higher absorption of 2, 4-D molecules by mycelia owing to the lower level of pH during culture.

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In the writer's previous paper, ^* he reported his experimental results on the turbidity of pressed-out juices from several plants, for the purpose of diagnosing viroses chemically and physically. The present report deals with the relation of the colloid stability to the turbidity of pressed-out juices from mosaic-diseased roots of radish and from crinkle-diseased potato tubers. The results obtained are summarized as follows.
The turbidity of the original pressed-out juices from healthy radish and potato was lower than that from diseased ones. The turbidity of juices kept standing for 8 hours was shown to be lower. In both cases when the radish or the potato was used, the diseased juice was more quickly clarified than the healthy, and the potato juice was found to be lower in its clarifying degree than the radish juice. (Table 1 and 4).
The centrifuged juice was found to be lower in its turbidity than the still-held juice, but the tendency toward clarification of the former was similar to that of the latter. (Table 2 and 5).
The quantity of precipitates (mainly protein substance) caused by the addition of saturated (NH₄)₂SO₄ solution was proportional to the degree of turbidity demonstrated in the above-mentioned experiments. (Table 3 and 6).
From the results obtained, the writer considers that the colloid stability of the pressed-out juice from virus-infected potato or radish is lower than that from healthy ones, and that this is in part due to the lower buffering capacity of the diseased juice.

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In this paper, the writers describe a new rust fungus parasitic on pea, which was collected in Hidaka, Hokkaido.
Uromyces Hidakaensis Murayama et Takeuchi, sp. nov.
Pycnidiis ignotis; aecidiis hypophyllis, rarius epiphyllis, aggregatis vel solitariis usque 2.5mm diam., saepe etiam in nervos et petiola elongatos evolutis, maculis orbicularibus vel ellipticis, 1∼3.5mm diam., flavidis insidentibus, cupulatis, ca. 220∼300μ diam., 100∼170μ altis, margine albido recurvato, laciniato; cellulis peridii firme conjunctis, polygonalibus vel rhomboideis, 19∼26×17∼22μ, pariete exteriore striato, 5∼10μ, interiore verrucoso 5∼7μ crasso; sporis angula-toglobosis, subglobosis vel ellipsoideis, minute verruculosis, subhyalinis, 14∼21×10∼18μ, episporio ca. 1μ crasso.
Soris uredosporiferis amphigenis et petiolicolis, plerumque hypophyllis, sparsis vel aggregatis, minutis, rotundatis, primo epidermide tectis, dein nudis, interdum confluentibus, pulverulentis, brunneis; uredosporis globosis, subglobosis, ellipsoideis vel obovatis, echinulatis, brunneis vel flavobrunneis, 20∼28×19∼25μ, episporio 1.5∼2μ crasso, poris germinationis 2∼5, plerumque 3∼4 sparsis praeditis.
Soris teleutosporiferis amphigenis vel petiolicolis, plerumque hypophyllis, sparsis vel aggregatis, minutis, rotundatis vel ellipticis, confluendo subinde majoribus, raro circinatim dispositis, primo epidermide tectis, dein ea fissa cinctis, pulverulentis, brunneis vel atro-brunneis; teleutosporis globosis, subglobosis, obovatis vel ellipsoideis, apice rotundatis, papilla hyalina praeditis, irregulariter verruculosis, brunneis, 20∼30×17∼22μ, episporio 1.5∼2μ crasso, pedicello hyalino, brevi, deciduo.
Hab. in foliis petiolisque vivis Pisi sativi L. (Endo) Higashi-Shizunai, Prov. Hidaka (Shoshiro TAKEUCHI, 20, 24, 30 Julio et 3, 8, Aug. 1950; 9 Julio 1951-typus; 6 Julio 1952.

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It has been shown that Phytophthora infestans uses the nitrogen-containing fraction as its main source of energy, especially the amino-acid of the host tissues, and can not grow on a synthetic medium unless thiamine is added.
However the optimum amount of thiamine varies with the amount of sugar in the medium and with other conditions.
The present experiments were carried out to study the nitrogen sources of Phytophthora infestans, using synthetic culture solutions containing thiamine hydrochloride. The results obtained may be summarized as follows:
1. Optimum concentration of thiamine hydrochloride for this fungus is about 1γ in 10ml of culture solution.
2. Nitrate is a good nitrogen source for this fungus. Ammonium salt is not good, probably because the fungus is not able to assimilate ammonium salt completely owing to the fall in pH of the medium which is resulted from the initial uptake of ammonia.
This fungus can not assimilate nitrite.
3. The various amino-acids and amides differ in value from each other as nitrogen source for this fungus.
Asparagine, l-aspartic acid, l-glutamic acid, l-arginine monohydrochloride are utilized more efficiently than nitrate.
The worth of glutamine, l-phenyl alanine, l-proline as nitrogen source is inferior to that of nitrate and dl-valine, l-isoleucine, l-lysine, dl-tryptophan, l-methionine, l-cystine, glycine and l-leucine are found inadequate for a nitrogen source.

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The effects of sulfadiazine on the infection of wheat seedlings by leaf rust, Puccinia triticina, were examined.
The development of uredosori on seedlings of the highly susceptible wheat varieties is remarkably inhibited by soil application of sulfadiazine-Na salt aq. at the rate of 40mg per 100sq. cm within 2 days after inoculation. With delay in application of the sulfadrug, rust-inhibitive effect decreased rapidly. Phytotoxic secondary effects, i. e. stunting of the plants and chlorosis of the leaves, were fairy marked at the effectual dosage. The effect of application before inoculation is well maintained for at least 9 days.
When wheat seedlings are sprayed to “run off” with the preparation up to a concentration of 1000ppm plus 1 per cent Tween-20 as a wetting agent, the development of sori is inhibited for some periods, but later on resumed gradually, the effect is very poor compared with that of soil application.
The rust-inhibitive effects of sulfadiazine are conteracted by the supply of p-amino benzoic acid.

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Successive microscopical observations were made on living sections stripped from the midrib epidermis of highly resistant potato variety 41089-8 (Solanum demissum × S. tuberosum) infected with Phytophthora infestans. These sections were placed between slide glass and cover glass supported with small glass rods, and mounted in water. Vital staining method with neutral red, and plasmolyzing method with sucrose solution were used to ascertain the moment when the host cell and intracellular hyphae die. If the sections are stripped with razor, when the invaded cells are still normal, or the contents already discolor but the granules are still in Brownian motion (4∼8hrs. after inoculation), the invaded cells discolor lightly in the course of successive observations, but do not become brown. The most of intracellular hyphae in these sections survive for a long time (average about 30∼50hrs., max. about 90hrs. after inoculation) and develop into the surrounding tissues. In the sections stripped when the invaded cells are still yellow or pale brown but granules have already stopped their Brownian movements, approximately a half of the intracellular hyphae have survived and subsist longer (average about 30hrs., max. about 50hrs. after inoculation) than those in intact tissue, but they are unable to grow further in the cell. In the case when intracellular hyphae are in touch with the cell wall, they grow occasionally toward the neighbouring cell in which the granules are still in active Brownian movements. Accordingly it is assumed that the growth of these hyphae has been inhibited mechanically by the gelation of host cell contents. In these sections, no more browning of the invaded cell are observed. It seems that, when the sections were stripped from the materials in which the invaded cells had already turned blackish brown, no intracellular hyphae were alive. In these sections, it was ascertained that the tissues around the injured cells survived for 1∼2 days after sectioning.
Following experiments were carried out to learn the reason why the browning process of invaded cell can not continue further in these living sections. The sections, invaded cells of which were in an early stage of alterations, were placed on pure agar in petri dish, and exposed to the air (oxygen) for 22 to 23hrs. The invaded cells in these sections showed discoloration, but could not accomplish the normal browning process, and the intracellular hyphae survived for a long time. These experiments show that inhibition of the browning process in these living sections is not necessarily due to the lack of oxygen, but to the loss of the active vital function.
Other experiments showed that increase of phenol compounds and activation in N-metabolism were seen in the tissues neighbouring the cells infected with phytophthora infestans, and these compounds were deposited continuously on the latter cells.
It seems that in the course of browning process, the continuous deposition of these compounds may result in the gelation of the cell contents, the sealing up of hyphae and finally the death of them. It may therefore be said that the “active vital function” described above is related to these processes.

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