Three triterpenoid alcohols: betulin, lupeol, and β-amyrin have now been isolated from the unsaponifiable fraction of the ethereal extract of the bark of Trochodendron aralioides Sie-bold et Zuccarini (Trochodendraceae). Of these, betulin has been further characterized as allobetulin. “Trochosterin”¹⁾, “an alcohol of m. p. 210°”²⁾, and “an alcohol (acetate: m. p. 170°)”³⁾, described by earlier groups of workers, have now been confirmed to be nothing other than a mixture composed of lupeol and β-amyrin respectively.

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Constituents of the acid fraction and their contents in the essential oil of the American, flue cured tobacco leaf (AFCTL) were determined and compared with those of the Japanese flue cured tobacco leaf (JFCTL)¹⁾. No difference was found in regard of the kind of volatile organic acid, except that AFCTL contained no α-crotonic acid. On the other hand, the content of the acid fraction in AFCTL was exceedingly higher than that of JFCTL, especially in low molecular fatty acids. Both n- and isovaleric acids could not be isolated and identified in AFCTL, as well as in JFCTL, but the presence of β-methylvaleric acid was also proved and it seemed that this acid might be one of the important constituents for the aromatic character of Virginia tobacco leaves.

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Acid fraction of the essential oil of Japanese flue cured tobacco leaf, before redrying and aging (BRA), was compared with that of the same leaf after aging (AA) as reported in previous papers^{1, 2)}. The organic acids which were isolated and identified in the essential oil of BRA are similar to those of AA, except that the former contains propionic and methyl-ethylacetic acids, which were not found in the latter. While, on the other hand, total volatile acids in AA was amounted to about three times as much as that of BRA, and especially the increase of acetic and phenylacetic acids was remarkable during the process of aging.

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The previously estimated carbonyl compoundt¹⁾ contained in the caustic alkali soluble-fraction of the essential oil of the Japanese flue cured tobacco leaf was identified as crotonal-dehyde, and the presence of α-pyrrylmethylketone in this phenol fraction was also proved. On the other hand, the constituents and contents of carbonyl and phenolic compounds, contained in this fraction before redrying, were compared with those of after redrying and aging. In the course of redrying and aging stages, phenolic compounds having the carbonyl group and the carbonyl compounds of this fraction increased, but the phenolic compounds having no carbonyl group decreased. Methylsalicylate could not be found in that fraction before redrying, but m-cresol was newly isolated and identified.

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The constituents and their contents of carbonyl compounds contained in the essential oil of Japanese Burley Tobacco Leaf (JBTL) were investigated and compared with those of Japanese Flue Cured tobacco leaf (JFCTL). Benzaldehyde, acetaldehyde, furfural, 5-hydro-xymethyl-furfural, isobutyraldehyde and C₆-aldehyde were isolated from the carbonyl-fraction in the essential oil of JBTL. A remarkable characteristic of the essential oil of JBTL is that benzaldehyde was proved as a predominant constituent and the content of furfural was ex-ceedingly smaller than that of JFCTL. 5-Methylfurfural, found in the essential oil of JFCTL, could not be isolated from that of JBTL.

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1) Experiment were conducted on the enzymatic action of the crystalline protease obtained from cultures of Ps myxogenes sp., and results obtained are as given below (2)-(4).
2) The optimum pH for liquefaction of gelatin was found to be 7.0-8.5, and the optimum temperature about 45°
3) The enzyme acted remarkably on gela-tin and hide-powder, but slightly on the other proteins, i.e., gluten, haemoglobin, casein, egg-albumin. The substrate-specificity is clearly differentiable from those of trypsin, papain and pepsin. Consequently, the enzyme may be assumed to be a collagenase.
4) From the mode of digestion of gelatin when the N-terminal residue technique was applied, it can be said that Ps enzyme is more similar to papain, than trypsin and pepsin. The author wishes to express his sincere thanks to Prof. H. Katagiri of Kyoto Univ. for his constant guidance and encouragement in the course of this work, and also to Mr. E. Masuo of this Laboratory.

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Rotundifolone C₁₀H₁₄0₂, the principal component of the essential oil obtained from Japanese Mentha rotundifolia, has been found to be 1-methyl-4-isopropylidene-1, 2-epoxy-cyclohexanone-3, which was reduced and rearranged to diosphenol. It is a noteworthy fact that the new ketone seems to be one of the intermediates between carvone series and menthone series.

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By means of the electrolytic reduction of diphosphopyridine nucleotide at controlled potential using mercury as the cathode, the author has obtained a product which showed an absorption spectra similar to that of dihydrodiphosphopyridine nucleotide. The optical density of the product at 340mμ diminished partly with the addition of alcohol-dehydrogenase and acetaldehyde or with that of malic acid-dehydrogenase and oxaloacetate as the oxidizing system. The same absorption band was completely disappeared by the addition of a fraction obtained from mung bean seedlings.

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A method for the micro amperometric determination of thiol-groups as small as from 0.1 to 1.0μ mole, corresponding to 10-100μg of cysteine, was devised. The thiol-group was titrated in ammoniacal solution in the stream of nitrogen with silver nitrate solution, using an ultramicroburette. The course of the titration and the end point was detected amper-ometrically using platinum vibrating electrode. The method was suitable for the determina-tion of a minute amount of thiol-groups, especially those found in plant tissues, which used to contain such substances as might otherwise disturb the determination. Contents of acid-soluble thiol compounds in etiolated mung bean seedlings at various stages of growth were determined by the method described here.

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In the tissue of silkworm the existence of an inhibitor of biological nitrate reduction has been demonstrated. This substance is heat-resistant and cannot be decomposed by autolysis. The inhibitor is contained, in the tissue of larvae, even in the acetone preparation, pupae, digestive juice and worm feces, but not in the blood and alimentary canal. When the worm is attacked with polyhedral virus disease or fed with nitrites, inhibiting ability of tissue is retained.
This inhibitor was isolated by extraction with diluted alkaline solution following pre-cipitation at about pH 4.2. On the basis of ultraviolet absorption spectrum and Murexide reaction, the inhibitor was deduced to be uric acid. Thence, the inhibiting action of uric acid was comparatively studied. Both the inhibitor isolated and pure uric acid diminished their inhibiting capacity by the pretreatment of mouse liver containing uricase, but not so in the case of fowl which has not such enzyme.
The reducing ability of larval tissue was attested by the removal of this inhibitor.

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