This paper deals with the results of studies on the aldehyde constituents in the oleoresin of Pinus densiflora.
   On the treatment of the oleoresin with Girard T reagent, the carbonyl material, which showed positive results in Schiff's test and silver mirror test for aldehyde group, was isolated in a yield of 0.15%. This material was oxidized with Tollens' reagent, and from the obtainable acidic portion, abietic acid and levopimaric acid were isolated and confirmed, respectively. Besides these acids, the presence of both neoabietic acid and palustric acid was slso estimated from the ultraviolet absorption spectrum.
   It is tentatively proposed that the oleoresin contains some abietic type diterpenoid aldehydes which are easily oxidized to resin acids mentioned above.

   A fully saturated sesquiterpenoid diol named cryptomeridiol was isolated from the heartwood of Cryptomeria japonica D. DON. The possible derivation of β-eudesmol (V) to cryptomeridiol has proved the structure (I) for the diol, which corresponds to that for the direct precursor of the eudesmane series of sesquiterpenoids suggested by HENDRICKSON. After completion of the work, it has been shown that cryptomeridiol is identical with the compound which had been isolated first from Widdringtonia dracomontana STAFF, by ERDTMAN and THOMAS and later from Fokienia hodginsii HEROUT and DOLEJS. HEROUT had proposed the structure (II) and the name, selina-4,7-diol for the compound, in which the stereochemistry at C-4 remained unsolved. Since the configuration of cryptomeridiol has been established as (I), it may be formulated as selinan-4α, 11-diol, numbering being as shown.

   It has been found that treatment of nootkatin with 85% phosphoric acid for more than five minutes affords almost pure nootkatinol. In the previous paper, nootkatinol was isolated from the wood of Juniperus rigida SIEB. et ZUCC. by treating the acidic portions of the extracts with 85% phosphoric acid. Therefore, reinvestigation on the wood extractive to determine the presence of nootkatinol in situ was carried out. As a result, it has been found that nootkatinol is still present in the extracts.

   The petroleum-ether soluble part of the methanol extract from the wood of Thuja standishii CARR. has been investigated. Although the methanol extract was obtained in a yield of 9.2 %, based on the oven-dry wood, the amount of the petroleum-ether soluble part was very small and about one twentieth of the total extract.
   Carvacrol, β-sitosterol, a paraffin hydrocarbon and a kind of carbonyl compound have been isolated, α-, β-Thujaplicins and an unidentified tropolone have also been shown to be present by paper chromatography.

   Gamma-irradiation of α-pinene in support of aeration results in formation of α-campholenic aldehyde, pinocarvone, pinocarveol, myrtenal and verbenone as major products, and of α-pinene epoxide and sobrerol as minor products. It is suggested that myrtenal, pinocarvone and pinocarveol result from free radical attack on the α-methyl group of α-pinene to give the myrtenyl free radical and its resonance hybrid the pinocarvyl free radical and the corresponding hydroperoxides, and that verbenone results from α-methylenic attack to give the verbenyl free radical and its hydroperoxide. α-Campholenic aldehyde and sobrerol are presumably derived from α-pinene epoxide which is considered to be a secondary product resulting from the action of a peroxide on the double bond of α-pinene.

   It has been found that nezukone (4-isopropyltropone) occurrs in the wood of Thuja plicata DONN.

   The essential oil from the heartwood of Thujopsis dolabrata SIEB. et ZUCC. has been investigated. There were isolated : β-thujaplicin, carvacrol, thujopsene, cuprenenes-2, -4, cuparene, α-, β- costals, cedrol, widdrol, three new sesquiterpenes, cuparenal, "Asunal", "Asunol", as well as an acid and four carbonyl compounds. The presences of γ-thujaplicin and a few phenols were indicated by paper chromatography.

   The essential oil of the wood of Kapur (Dryobalanops sp.) has been investigated. (−)-Limonene, p-cymene, (−)-isoborneol, bornyl acetate, cis- and trans-β-terpineols, (−)-borneol and (−)-α-terpineol were isolated. The presence of α-pinene, camphene and β-pinene was indicated by gas chromatography.

   The essential oil of the wood of Kapur was investigated and the presence of some monoterpenes was reported in the previous paper. In this paper, from the residue from which monoterpenic fractions had been distilled, six kinds of triterpenes have been isolated and named the crystals A, B, C, D, E and F. And their physico-chemical properties have been investigated.

   In order to compare Thuja species from the viewpoint of chemotaxonomy, the essential oil from the wood of Thuja koraiensis NAKAI has been investigated, α-, β-, γ-Eudesmol, occidentalol, occidol and occidiol, all of which have been recognized in Thuja occidentalis L., were isolated as well as nezukone, whose occurrence in Thuja standishii CARR. and Thuja plicata DONN had been shown. Besides the above compounds α-terpineol, terpinene-4-ol and cryptomeridiol were also isolated. The inconsistency of the tentative structure proposed for occidiol by RUDLOFF and NAIR was also indicated.

   The essential oil from the wood of Biota orientalis has been investigated in detail. The presence of sesquiterpenoids containing nine new components as listed in Table 1 was indicated. From the standpoint of chemotaxonomy the botanically monotypic Biota seems to be similar to Juniperus rather than to the other closely related conifers, since only sesquiterpenes of the cis-farnesyl type are found likewise in Juniperus.

   The sesquiterpene hydrocarbons in the wood of Juniperus rigida are listed in Table 1. It is the first case and of significance from the viewpoint of chemotaxonomy that the presence of the trans-farnesyl type sesquiterpenes (β-elemene and β-selinene) are detected in the wood of the Juniperus species.