A bottle culture method is described which favours the colony formation of Leptospira icterohaemorrhagiae. The Kitakata strain formed two morphological types of colonies when grown in rubber-stoppered 200ml-square bottle cultures. One was compact and small (C type), while the other diffuse and large (D type). The C and D type sub-strains showed the following differences: The C type leptospirae were longer in body length, but less virulent for suckling mice, young hamsters, guinea pigs, or young rabbits. The C type leptospirae lost 90% of the colony forming units (CFU) after being heated at 45 C for 20 minutes. On the other hand, the D type leptospirae were shorter in body length, virulent in those animals examined and resistant to heating. No serological differences were observed between these two types of sub-strains by agglutination test and in agglutinin absorption test.

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An increase in the inhibitory effect against infection by TMV was found in the juices extracted from the primary leaves of French beans previously inoculated with active TMV or ultraviolet-inactivated TMV as compared with that of the control leaves. No difference in the induced inhibitory effect was observed between active and ultraviolet-inactivated preparations of the necrotic and ordinary strain of TMV, however, the interfering activity of active TMV was greater than that of ultraviolet-inactivated TMV when boh strains were inoculated simultaneously on the leaves of French beans. These phenomena were not produced by TMV inactivated by heating at 100C for 10 min. Further, it was ascertained that there was an increase in the inhibitory effect found in the juices from the uninoculated apical or basal parts and petioles of inoculated leaves when the other parts of the leaves were inoculated previously with TMV. Similarly, the induced inhibitory effect was found in the plumules produced at the base of the TMV-inoculated leaves.

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The fine structure of conidiospores of Aspergillus niger has been studied by means of ultrathin sectioning and electron microscopy. Permanganate fixation of the conidia preserved the details of their inner structural components and enhanced the general contrast within the sections. The conidiospores are characerized by their peculiar surface structures composed of three distinct components; an outer hull, a spore coat or wall, and an intermediate space. As a consequence of the swelling of the conidia, both the outer hull and the intermediate space almost completely disappear, and a variety of the intracytoplasmic organelles becomes visible in large numbers. The mature conidia at the resting stage appear to possess a more electron-dense cytoplasm than that of the parent hyphae of the organism. They also contain a nucleus and a few mitochondria within the cytoplasm. The significance of these structures and their relationship to the parent hyphal cells are discussed.

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Examination of cross resistance to macrolide antibiotics in erythromycin resistant staphylococcal strains isolated from clinical sources in the United States showed that there were two types of cross resistance, group A (13.4%) and group C (86.6%). Group A possessed multiple resistance to the macrolide antibiotics, erythromycin, oleandomycin, leucomycin and spiramycin, and was also resistant to lincomycin. In group C, resistance to erythromycin alone or to both erythromycin and olcandomycin could be induced by exposure to erythromycin.

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Cytopathogenic agents have been isolated in a search for viruses in the feces of apparently healthy mice (an inbred strain DK1) by using mouse kidney tissue culture. This report is concerned with the identification of strain K87, one of our isolates, as an adenovirus. Strain K87 was cytopathogenic to mouse kidney tissue culture but not to monkey kidney tissue culture, FL, and HeLa cells. The K87 strain was not able to grow in bacterial media and was resistant to penicillin, streptomycin and tetracycline. 5-Bromo-deoxyuridine inhibited the occurrence of the cytopathogenic effect and virus replication in infected cells and the inhibitory effect was reversed by thymidine, suggesting that the virus contains DNA. Strain K87 was resistant to ethyl-ether but did not have the property of cationic stabilization to thermal inactivation. Electronmicroscopic observations of thin-sections of the K87-infected cells showed virus particles in crystalline array in the nuclei. Each virus particle was an icosahedron of about 75mμ in diameter composed of 252 capsomeres, and without an envelope. By the complement fixation test, K87 was related serologically to a human adenovirus. All the facts indicate that strain K87 belongs to the adenovirus group. The problem whether strain K87 may be a new mouse adenovirus with pathogenicity and antigenicity different from that of a mouse adenovirus previously reported by Hartley and Rowe is discussed.

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