As shown in the previous paper (1), it was found that antibodies in the serum from which lipid was removed by the extraction process of Horsfall and Goodner (2) could bind with antigen, without showing the agglutination. From the viewpoint of lattice theory it was very strange, because if antibodies can bind with antigens, then the agglutination should always occur. But the disappearance of agglutination after extracting lipid suggests that, though antibodies bind with antigens, lipids are necessary for the formation of large aggregates of antigen-antibody complex.
The classical work of Northrop and De Kruif (3) has shown that sensitized bacteria behave like hydrophobic colloidal suspension and are agglutinated when their electrokinetic potential is lowered under 15 mV. by the salt in the medium. The work of these authors seems to suggest that antigen-antibody complexes become larger when their surface potential is lower than 15 mV.
In the present paper, the experiments testing the effect of lipid on the surface potential of antigen-antibody complex are described. The disappearance of agglutination after extract-ing lipid can not be ascribable to the change of the surf ace potential. The surface potential of the antigen-antibody complex seems to be rather independent from lipid. The role of lipid in the agglutination is also discussed in this paper.

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Waksman and his collaborators (1) found that streptomycin-producing strains were much more resistant to streptomycin than other strains of streptomyces, and the isolation of streptomycin-producing strains became much easier. After a chloromycetin-producing strain was isolated by us (2), the further isolation of such a strain has been very difficult. During testing resistances of antibiotic streptomyces to chloromycetin, we found that the chloromy-cetin-producing strain was more resistant to chloromycetin than other strains. So in further trials of isolating chloromycetin-producing strains, the soil was streaked on the nutrient agar added with chloromycetin. Then from colonies growing on the agar chloromycetin-producing strains were easily obtained.

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After streptomycin had been isolated from S. griseus, Reynolds, Schatz, and Waksman (1) found another strain of S. griseus which produced a new antibiotic. This antibiotic substance, called grisein, is adsorbed by activated carbon and eluted into neutral 90% alcohol and inhibits the growth of gram positive and negative bacteria, though its effective range is narrower than that of streptomycin.
As reported in the previous paper (2), antibiotic strains of streptomyces could be differentiated by testing their antibacterial spetra, and several strains of S. griseus were found to be showing an antibacterial spectrum different from streptomycin-producing strains. In this paper studies on such strains and their antibiotic substance are described.

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From the fermented broth of a new species of streptomyces Umezawa, Maeda and Kosaka (1) obtained a golden yellow crystalline antibiotic and called it aureothricin. This antibiotic inhibits the growth of gram-positive and negative bacteria and is clearly different from yellow antibiotics of streptomyces such as aureomycin (2) and xanthomycin (3) . In the present paper its purification and chemical characters are described.

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It has been known since the 19th century, that most luminous bacteria have their greatest luminescence in medium containing 2-3 per cent NaCl. But the relation between the luminescence and the concentration of NaCl was not systematically studied until 1932. In that year F. Fuhrmann (1) found that the optimum concentration of NaCl for both growth and luminescence was 0.3-0.4 N, and that of NaBr for growth was 0.5-0.6 N and for luminescence was 0.4-0.6 N, using Photobacillus radians isolated from North Sea fish. In 1933 T. Kishitani (2) found that a luminous bacterium, Pseudomonas phosphorescens, had its maximum growth in the medium containing 1 per cent NaCl, and the maximum light production per unit cell of the bacterium occurred in the medium containing 5 per cent NaCl, but the maximum, light production per unit volume of medium occurred in the medium containing 3 per cant NaCl. In 1939 M. Takase (3) precisely measured the luminescence intensity of bacterial suspension in various salt solutions. He found the maximum luminescence intensity per unit suspension occurred in 0.5 N NaCl solution, and the optimum concentration of NaBr was 0.5N. He also observed that the action of chlorine ion was much greater than that of bromine ion at equivalent concentration of sodium salt.
The author determined the optimum concentration of NaCl and NaBr for growth and luminescence.

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