A study was made on the colorless needle crystals (named "crykonisine"), m.p. 235~236° (decomp.) of the alkaloids isolated from Cryptocarya Konishii HAYATA (Japanese name "Konishi-gusu"). Crykonisine shows: α)28 ± 0° (EtOH), C18H17O3N, two OCH3 groups, one phenolic hydroxyl group, and real benzylisoquinoline type bases of UV absorption spectrum (Fig. 2), tetrahydro derivative treated with zinc powder in HCl shows [α]B25 ± 0° (CHCl3), colorless needles, m.p. 139 ~ 140°, which is identical with dl-N-norarmepavine (II). Therefore, the structure of crykonisine has been determined as 1-(p-hydroxybenzyl)-6,7-dimethoxyisoquinoline (I).On the other hand, an investigation was made on the alkaloids from the rootwood and root bark of Machilus acuminatissima (HAY.) KANEHIRA (Japanese name "Usuba-tabu", Chinese name "Chien-yeh-nan") and L(-)-N-norarmepavine, dl-N-norarmepavine, dl-coclaurine and crykonisine (I) from rootwood, and L-(-)-N-norarmepavine and dl-coclaurine from root bark roots were isolated and have been confirmed. (Table I)