The antigenical differences among several strains of Rickettsia orientalis have already been reported by many workers. At first, Bengtson (1945, 1946) differentiated Karp (New Guinea), Seerangayee (Malaya), and Gilliam (Burma) strains of Rickettsia orientalis by complement fixation, and later Philip (1947) observed that sera of patients of tsutsugamushi disease in Japan could be divided into two different types (Karp and Gilliam types) by complement fixation reaction. On the other hand, Bell et al. (1946), Bennett et al. (1949), and Fox (1949) demonstrated independently the heterogeneity of several strains by cross-neutralization test, and similar results were obtained by Right et al. (1948) in their cross-vaccination studies. By these findings, the causative agent is usually identified by demonstrating resistance of convalescent animals to approximately 100 LD₅₀ of a known strain of scrub typhus, because subcutaneous inoculation of the agent into animals induces an inapparent infection which is followed by immunity, and the resistance of convalescent animals to reinfection is found to be almost common among all strains so far tested.
But in the protection test, there has been left a criticism that the resistance of convalescent animals might be explained just as reasonably as a manifestation of interference phenomenon (Fox, 1949) .
In the previous report (Shishido et al., 1958), it was analysed that the resistance of mice surviving subcutaneous infection of Rickettsia orientalis (Kato strain) to reinfection of the same agent was caused by immunity acquired by the initial infection, although such immunized mice could maintain a nonspecific resistance (interference) to superinfection of a heterologous rickettsia (Rickettsia mooseri) and a virus (Meningopneumonitis virus) .
The present paper deals with the results of cross-protection tests among many strains suspected by us as Rickettsia orientalis on the criteria of morphological characters and general properties of the agents. Most of these strains were recently isolated from field rodents trapped at many different areas of Japan for the epidemiological studies of scrub typhus in Japan designed by Dr. Tamiya et al. (1955, 1956, 1957, 1958) . At the same time, a strain, which was isolated from a rodent trapped in Hokkaido, an island located in the north-eastern part of Japan and to which the name of Rickettsia tamiyai was proposed by Kawamura (1954a, 1954b), was tested in comparsion with those newly isolated strains. From the present results, the authors concluded that all strains including Rickettsia tamiyai were to be identified as Rickettsia orientalis, although a minor difference was observed in some strains.

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In special reference to the production of the soluble antigens, the details on the mode of growth of vaccinia virus in HeLa cells were reported by Tagaya and Oda (1958) . When HeLa cells were infected with a heavy inoculum, the first appearance of measurable complement fixing antigen in the cell homogenate was 6 hours following infection and another soluble antigen, hemagglutinin, became measurable 5 hours later. A significant rise in titer of infective virus within cells was noticed at nearly the same time, when hemagglutinin became measurable in the cell homogenate. Based on the morphological observations of the intracellular development of poxviruses by use of electronmicroscope, Higashi et al. (1959) reported that matrix appeared in cytoplasm 3 hours following infection and that the first recognizable viral form, so-called developmental form, was observed within the matrix area in the cells harvested 6 hours after infection. Advance in the biochemical analyses of phage-infected bacteria stimulated the same line of research works in animal viruses, but due to the difficulties inherent in animal viruses and animal cells, not so many reports have ever appeared, i. e. on poliovirus (Maassab et al., 1957; Miroff et al., 1957; Ackermann et al., 1959; Salzman and Lockart, 1959), herpes simplex virus (Newton and Stoker, 1958) and adenovirus (Ginsberg and Dixon, 1959) . As regards vaccinia virus, Magee and Sagik (1959) reported that C¹⁴-thymidine was incorporated into the DNA fraction of vaccinia-infected HeLa cells, and Chang (1959) concluded from the experiments on bicarbonate-deficient tissue culture that ribonucleic acid might play an important role on the synthesis of vaccinia virus.
In this communication the authors present the data concerning the metabolic alterations in HeLa cells infected with vaccinia virus. The experimental results indicate that a marked incorporation of radioisotope phosphorus into acid-soluble fraction was observed in the early stage of infection and that the maximal incorporation into ribonucleic acid fraction was delayed by several hours. Furthermore, chemical analyses of labeled nucleotides demonstrate that the radioactivity was considerably increased in the cytidine-diphosphate and adenosine-triphosphate fractions of the infected HeLa cells as compared with that in the corresponding fractions of the control cells, while the situation was contrary with adenosine-monophosphate.

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During the summer of 1959, many cases were reported from Tokyo area of accidental dermatitis caused by contact with a kind of hairy caterpillars, which crowd on bamboo leaves growing in the garden. These caterpillars were identified as the larva of a zygaenid moth, Artona funeralis Butler, which is distributed from Hokkaido to Kyushu and is sometimes known as a pest of bamboos. It was revealed from literature and information that local outbreaks of this larva have occurred mainly in the southern part of this country. It has further been believed that the dermatitis may be caused by some sort of poisonous hair on the larva, but no attempt has ever been made even to ascertain which hair on the larva is responsible.
In the present study were described some results of morphological and histological observations on the poison hair and of a series of experiments on its possible sting mechanism.

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As shown in the preceding reports (Horiuchi et al., 1959 a; Horiuchi, 1959), the RNA of E. coli degraded by 30% during 3 hours after the exhaustion by the bacteria of phosphate in the medium. Some enzymes presumed to be correlated with the degradation of RNA, such as RNase, phosphodiesterase and PMase, were estimated with the result that a remarkable formation of PMase was observed (Horiuchi et al., 1959 b) . A brief note of this enzyme formation considered to be as a negative feed back mechanism was already reported (Horiuchi et al., 1959 b) . Independently, Torriani (1959 a, b) and Hofster (1959) observed the same phenomenon and Garen and Levinthal (1959) highly purified the PMase.
The present report deals with some details of the PMase formed during the phosphate deficient phase of E. coli. The results obtained revealed that there is no direct correlation between the degradation of RNA and the formation of PMase and that no factors so far tested other than phosphate deficiency could induce the PMase formation.

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In a previous report (Abe and Mizuno, 1959), the author demonstrated that the appearance of Pneumococcus transformants (SM resistant) followed a normal distribution during the time course after the addition of DNA. In an attempt to elucidate the relationship between the appearance of SM-resistance and the participation of nucleic acid synthesis in the course of this transformation, the author has examined the effect of several inhibitors of nucleic acid on the process. Among the inhibitors examined 8-azaguanine revealed a marked effect of decreasing the number of transformants once formed, suggesting the presence within the transformant cells of an intermediate stage in which the cell can be reversed to SM-sensitive by 8-azaguanine. The present report will describe the details of this result.

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We have been studying on combination chemotherapy against cancer in experimental animals by means of an expected synergistic effect of several drugs which are assumed to act in different modes. The brief mode of action of some known anticancer drugs is urgently needed to be elucidated. Twenty-one anticancer drugs were submitted to the test of some unbalanced inhibitory effect on the syntheses of nucleic acid and of protein of E. coli. Our emphasis was mainly put on the inhibition of the anabolism of the organism, though the effect on the respiration was compared. Mitomycin (Shiba et al., 1959) and RC-4 were found to be specific inhibitors of DNA synthesis and 4-nitro-quinoline N-oxide was that of RNA synthesis. In addition, some other specific inhibitors of protein were observed.
The effect on the cancer cells will be reported in the next paper.

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While there have appeared many reports on screening of synthetic drugs for cancer chemotherapy, not a few chemical compounds are being synthetized throughout Japan with no chance to be subjected to anti-cancer screening. To fulfill the demand to establish a screening system for such new compounds, a plan of “screening service” has recently been realized in the National Institute of Health, Tokyo. Approximately 2000 synthetic chemical compounds of various kinds have been collected and examined for their anticancer effects. The activity of this service system will probably be expanded so that it could cover test samples from all over the country in the future. There should be several problems to be considered from the methodological viewpoint. At the present, however, within the limit of utilities with which to start the investigation, it was unavoidably required to simplify the screening procedure so as to deal with as many samples as possible.
In the present paper, the process of standardization of the procedure for our anticancer screening system will be described. The following paper (Takano et al., 1959) will present the result of screening obtained with some naphthoquinone derivatives.

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