The nutritional effects of several kinds of oils of plant or animal origin on the larval growth of silkworm, Bombyx mori, were examined. It has been found that chlorogenic acid considerably fortifies the growth promoting effect of various oils, and also that cottonseed oil and peanut oil show a strong growth stimulating activity.

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The absolute methanol extract of mulberry leaf powder contains a previously unknown fat-soluble growth promoting factor for the silkworm, Bombyx mori. This factor was purified and identified as the mixture of palmitic acid and linolenic acid. The addition of each of the acids individually rather inhibited the larval growth. The combination of stearic, oleic, or linoleic acid with linolenic acid also showed growth stimulating effect. The activity of the mixture of methyl palmitate and methyl linolenate was very slight.

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Employing microelectrodes and isolated rabbit right atrium, the sites of conduction block were examined by increasing the potassium content of the Tyrode solution.
The conduction block occurred first in the whole left atrium and the right atrial portions closer to the atrioventricular groove. Next conduction block appeared in the extension of the upper branch of the crista terminalis near the atrial septum. In the third stage of block it was seen on the atrial septum side and in the adjacent caval region, including the septal side of the upper and lower branches. In the terminal stage of block the excitation wave from the sinus node could reach the crista terminalis, but it could not go much farther.
The fact that the sinus node area was found to be the most resistant in these experiments suggests that the so-called sino-atrial block observed clinically in the electrocardiogram may actually be intra-atrial block.

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The distribution of ²⁰³Hg into rat tissue after single oral administration of ²⁰³Hg-phenylmercuric acetate was studied. Percentage of ²⁰³Hg found in the tissues to administered mercuric compound at 24-hour was as follows: 10% in the kidney and in the intestines, 3% in the liver, 2% in the blood, and 1% in the stomach. The accumulated ²⁰³Hg in the intestines, the stomach, and the blood diminished markedly in next 24 hours, however, decrease of ²⁰³Hg in the kidney and the liver was not so distinct. Small amount of ²⁰³Hg was found in the brain, the heart, and the spleen at 24 and 48-hour, but was not at all at 96-hour. By administration of BAL, the above tendency was almost unchangeable and total accumulated amount of ²⁰³Hg in animal decreased slightly.
In the kidney and the liver, the largest amount of ²⁰³Hg was distributed in the supernatant by centrifugation fractionation.

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A 7 year old mentally retarded girl showing the typical signs of Down's syndrome, and her clinically normal parents were studied cytogenetically. It was found that the patient showed trisomy for one of the G group chromosomes, and that one of the trisomic elements is characterized by a deletion of the short arm. Her phenotypically normal mother was found to possess a short arm deleted chromosome of a similar type in G group. Her normal father possessed a normal male complement.

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Hamster embryonic cells were cancerized successfully by treatment in vitro with 4-NQO, 4-HAQO, and 6-chloro 4-NQO. The characteristic changes appeared in the cells 2 or 3 days after the treatment with carcinogens such as necrosis and criss-crossed arrangement of fusiform cells. These early changes were later followed by morphological transformation, i.e., the appearance of transformed foci in which the cells grew actively, piled up and formed dense layer. Malignization of these cells was confirmed by transplantation into newborn and adult hamsters. The animals died of tumor, sometimes with metastasis. The time required for the malignization of normal cells was different, depending on the frequency of treatment and given amount of carcinogen. It was noteworthy that even one single treatment of 4-HAQO could induce the malignization of normal cells, although it took longer time. In the untreated cultures, no transformed cells were found. The control cells revealed a monolayer growth of fibroblastic cells, which was later followed by a non-proliferating state of large, flat and granulated cells. The control cells failed to produce tumor in animals.
The techniques of in vitro system on experimental carcinogenesis seem to be a useful and new approach to uncover various problems in carcinogenesis, especially the early stage of cancer development, i.e., cancerization of normal cells to malignant.

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