Ultrathin sections of yeast cells of Cryptococcus neoforrnans, fixed in osmium tetroxide or in potassium permanganate, have been prepared and examinedwith the electron microscope.
The cell wall consists of several layers. The outer and inner layers of the wall are composed of electron dense material, and they surround the middle layer of lesser electron density. Furthermore, the inner layer is subdivided into several strata by fibrillar electron-dense structures.
The cytoplasmic membrane is present just beneath the cell wall and projects undulantly into the cytoplasm.
The nucleus is bounded by a double membrane with pores, and it lies near the middle of the cell body. No electron dense body, which is characteristic of a nucleolus, is obserevd within the nucleus.
Mitochondria are present in the periphery of the cytoplasm adjacent to the cytoplasmic membrane. They are surrounded by a double membrane and the parallel lamellae which probably correspond to the cristae mitochondriales projecting from the inner layer of the membrane.
Moreover, well defined electron-dense areas which appear to be the lipid granules are shown in various places of the cytoplasm.
In order to obtain the best materials demonstrating the finer inner structures of yeast cells, the ultrathin sections of the organism fixed in potassium permanganate should be prepared in addition to that fixed in osmium tetroxide.

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1. Transmission of the R-factor from Shigella flexneri 2b 103 R₄ to newly isolated strains of Vibrio comma and Vibrio El Tor was confirmed.
2. The old stock strains of Vibrio comma and Vibrio El Tor did not serve as the recipients of the R-factor.
3. CM-and TC-resistances of Vibrio comma and Vibrio El Tor receiving the R-factor were generally lower than those of the donor.
4. The retransmission was accomplished from some strains of Vibrio comma and Vibrio El Tor, which received the R-factor from Shigella, to Salmonella typhi T-10 and Shigella flexneri 3a MZ. Furthermore, the tertiary transmission from these recipients to Escherichia colt CSH was possible. Salmonella typhi and Shigella flexneri, recipients in the retransmission, and Escherichia coli, recipient in the tertiary transmission, manifested drug resistance nearly as high as that of the original donor, Shigella flexneri 2b, strain 103 R₄.

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1. 4-Nitroquinoline N-oxide (4-NQO) induced the production of respiration-deficient (RD) mutants of Saccltaromyces cerevisiae.
2. In the RD mutants, induced by 4-NQO, cytochromes a and b disappeared and c was decreased. The respiration capacity of RD mutant was depressed and anaerobic fermentation was strikingly increased.
3. The RD mutant induced by 4-NQO was more sensitive to nitromin, mitomycin C and 4-NQO than the acriflavine-RD mutant or parent yeast.
4. The toxohormone-like substances was found in the RD mutant induced by 4-NQO.
5. In the comparative experiments of the 4-NQO and its related compounds, some parallel relationship between the induction activity of the RD mutant and carcinogenicity existed.

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Leptospira and Treponema pallidurn were easily stained by a basic fuchsin solution after treatment with a sodium bicarbonate solution. This simple staining method enabled the observation of leptospiral cell, its granules and the agglutination-lysis reaction.

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