A poisonous seed or nut whose active principle is the alkaloid strychnia. It is best used in extract or tincture. Both are bitter tonics, with a powerful action on the nervous system, especially the spinal marrow. Leaving what we may have to say about this last action until we come to strychnia, it may be mentioned that physicians often find extract of nux vomica a good addition, in small dose (a quarter to half a grain), to tonic pills for continued debility. The tincture, in ten-drop doses, in water, is an excellent medicine for great weakness of stomach, with flatulence. Larger doses (if even these) should not be ventured upon without medical advice; on account of the very powerful nature of the active principle of this drug. The tincture of nux vomica should be marked "poison."