Strychnine (C21H22N202), the principal alkaloid obtained from the seeds of the nux vomica tree (Fig. 177), is one of the bitterest substances used in medicine. One part of strychnine gives a bitter taste to 700,000 parts of water. It is one of the most violent poisons, but in minute doses is highly valued as a tonic by physicians.

Fig. 177, I. Nux Vomica (Strychnos Nux vomica, Logania Family. Loganiacece). Flowering branch. (Baillon.) Tree of moderate height; leaves glossy; flowers greenish or yellow; fruit orange. Native home, India and East Indies.

Fig. 177, I.-Nux Vomica (Strychnos Nux-vomica, Logania Family. Loganiacece). Flowering branch. (Baillon.)-Tree of moderate height; leaves glossy; flowers greenish or yellow; fruit orange. Native home, India and East Indies.

Fig. 177, II. Nux Vomica. A, flower bud. B, same, cut vertically. C, floral diagram. D, fruit cut across. E, seed, entire. F, same cut through embryo between seed leaves.

Fig. 177, II.-Nux Vomica. A, flower-bud. B, same, cut vertically. C, floral diagram. D, fruit cut across. E, seed, entire. F, same cut through embryo between seed-leaves. (Baillon.)