The fresh tops of Thuja occidentalis.

Characters. - Twigs flattish, two-edged, the scale-like leaves appressed and closely imbricate in four rows, rhombic-ovate, obtusely pointed, with a roundish gland upon the back; of a balsamic, somewhat terebinthinate odour, and a pungently aromatic, camphoraceous, and bitter taste.

Dose. - Of a saturated tincture or fluid extract 1 fluid drachm.

Action. - The twigs of thuja, like those of savin, may produce abortion. They probably have no direct specific action on the uterus itself, but cause great gastro-intestinal irritation, and thus act on the uterus reflexly. The oil of thuja has an action somewhat like camphor, and like it produces epileptiform convulsions in warm-blooded, and paralysis in cold-blooded animals. Both camphor and oil of thuja have only a slight action on the heart. They both produce rhythmical contraction and dilatation of the vessels (as seen in the rabbit's ear). Both lessen the temperature (Kohne) (cf. p. 1019).

Uses. - It is diuretic, astringent, and aromatic, and its volatile oil has been used as a vermifuge. It has been employed in the form of a decoction in coughs, rheumatism, dropsy and amenorrhoea.