The data are given for the concentration of the three riboflavin fractions in several major tissues(liver, kidney, heart, lung, brain, spleen, gastric muecle, intestines and testicles), of both normal and riboflavin-defficient rats. Riboflavin content of the liver, kidney and heart of normal rat was about 20-30μg/g., and much lower in other tissues. In general, the majority of total riboflavin content, including free riboflavin, FAD and FMN, was FAD amounting to 65-85 per cent, while the remainder was almost FMN, and free riboflavin was insignificant in all the tissues. In riboflavin-defficient rat, all the three riboflavin fractions decreased, and the most significant decrease was found in FAD of the liver, kidney and heart. No significant change was recognized in the ratio of free riboflavin : FMN : FAD in the riboflavin-defficient tissues examined as compared with that of normal tissues.

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To elucidate the mechanism of increase in the serum vitamin B_<12> concentration in acute hepatitis or hepatic necrosis, this experiment was performed. In rabbits, a single subcutaneous injection of 0.5 or 1.0ml of 20 per cent solution of carbon tetrachloride per kg caused liver damages developing in a day or two. The central lobular necrosis was most characteristic of the damages, and the accumulation of fat and the disappearance of glycogen and pyroninophilic substance in central zones and mid-zones were histochemically observed. In the period when the hepatic damages were developing, the serum vitamin B_<12> concentration, especially that of the bound form, increased remarkably and simultaneously the content of the vitamin in the liver decreased. The increase of the vitamin contents in the total serum was almost the same in extent as the decrease of the vitamin in the total liver. The increase of the serum vitamin B_<12> began to decline after about ten days until returned to normal value on the 31st day. The content of the vitamin in damaged liver recovered gradually from deficiency, but the rate of recovery was slower than that of the histological damages. Vitamin B_<12> in normal rabbit liver cells is distributed mainly in mitochondria and in the cells of the damaged liver the vitamin in this fraction decreases. From the facts obtained in these experiments it may be postulated that when the liver cells are damaged to acute necrosis vitamin B_<12> in the cells is rapidly released into blood stream and pathologic high levels of the serum vitamin B_<12> occur.

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Vitamin B_<12> content of human liver tissue resected at Iaparotomy was determined in some abdominal diseases, mainly cancer of the stomach, by the microbiological method using L. leichmannii. The range of the vitamin content of normal human liver was from 0.60 to 0.85μg per g. of wet weight. When liver function tests, especially urine quantitative Millon's reaction and bromsulphalein clearance test, revealed disturbance of liver functions before laparotomy, the vitamin content of liver tissue was decreased in contrast when liver function tests did not show any abnormality. In gastric cancer low vitamin B_<12> level of liver tissue was usually found in markedly advanced cases which were mostly complicated with cancerous peritonitis. The serum vitamin B_<12> level in various diseases examined here was almost within normal range, but in a few cases showing marked disturbances of liver functions and decreased liver vitamin B_<12> level the serum vitamin B_<12> level was high. Severity of morphological damages of mitochondria in liver cells was in good accordance with the degree of disturbance of liver functions and with the extent of decrease of vitamin B_<12> content of liver tissue. These facts were also seen in experimental liver iniury by CCl_4 in rabbits. Although the preventive effect of vitamin B_<12> on the liver injury be CCl_4 was demonstrated in experiments of rabbits, the effective dose of vitamin B_<12> was excessively large.

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For the purpose of studying the influence of antivitamin B_6 on the tryptophanase of surviving cells of Escherichia coli, the conditions requisite for the enzyme production, enzyme activity and indole production were observed, and the use of simple condition giving a good result for the determination of indole was suggested.

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The action of tryptophanase of Escherichia coli, both wild and pyridoxineless type, was inhibited by isonicotinyl hydrazide and 2-methyl-4-amino-5-hydroxymethylpyrimidine (OMP), but not by 4-desoxypyridoxine. The inhibitory effect of INAH on the tryptophanase was prevented only by vitamin B_4 among many vitamin tested, but the inhibition due to OMP could not be checked by vitamin B_6. These findings are not consistent with those concerning the growth inhibition of lactic acid bacteria.

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FAD was produced by Eremothecium ashbyii in the yield of 60-120mg per liter of culture medium containing 1% of glucose or sucrose, 1.5% of peptone and 0.1% of corn steep liquor. A large portion of FAD was contained in mycelia and the content was 20-40 mg per g on a dry base. Nearly the same results were obtained using a fermenter of two tons in capacity. If sugar, peptone, corn steep liquor or inositol was supplied in excess the growth of fungi was accelerated and the content of FAD was decreased. When digested star fish was supplied instead of peptone, the growth of mycelia was incresed not affecting the FAD content.

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