Active Ingredients. - The alkaloids strychnia and brucia (are said to) represent all the powers of nux-vomica.

Strychnia is colorless, and crystallizes out of an alcoholic solution in four-sided, right-rhombic prisms, with four-sided pyramidal apices. It is very insoluble in water; more soluble in alcohol of sp. gr. .863, especially when this is heated to, or nearly to, the boiling-point. The solution is intensely bitter, and leaves a metallic after-taste, which is very characteristic. Strychnia is one of the alkaloids which dissolve without change of color in pure concentrated sulphuric acid: but if a single crystal be thus dissolved on a white plate, and a drop of solution of some deoxidizing substance (e. g., bichromate of potassium), be made to mingle at its edge with the dissolved strychnia, there is presented a perfectly unique play of colors, including blue, purple, crimson, and red-brown; all this passes in a few seconds, and then the red-brown gradually fades into a light red, which is persistent for some hours.1 The formula of strychnia now generally accepted is C21H12N2O2

Strychnia is a powerful base, completely neutralizing the strongest acids, and precipitating many metallic oxides from their solutions as salts; not unfrequently double salts are formed. Strychnia salts are mostly crystalline, and always intensely bitter.

Brucia (C23H16N2O4) forms exceedingly transparent four-sided prisms, or, if the solution be more hastily evaporated, pearly scales that resemble boracic acid, or which form a cauliflower-like mass; the taste is strongly and persistently bitter; it is soluble in 500 parts of boiling, or 850 of cold water. Brucia and its salts are both turned scarlet or blood-red by strong sulphuric acid.

(In addition to strychnia and brucia, Desnoix, in 1853, discovered a third alkaloid, to which the name of igasuria has been given. It is soluble in one hundred parts of hot water, from which a portion of it is deposited on cooling. It is very soluble in alcohol, chloroform, and essential oils. Its ultimate analysis has not been satisfactorily determined. If brucia be heated with iodide of methyl, a combination, called iodide of methyl-brucia, is formed.)

Physiological Action of Strychnia. - The action of this alkaloid very nearly represents the whole activity of nux-vomica, the effects of brucia being a weak though perfect copy of those of strychnia. (Igasuria stands midway between strychnia and brucia.)

Given in anything like massive doses, strychnia produces powerful and characteristic tetanic convulsions. The first symptoms are developed in from a few minutes to an hour after the administration; the patient feels a sudden sense of suffocation and dyspnoea; the head and limbs begin to jerk in a shuddering manner; the limbs are then suddenly stretched out rigidly; the hands are clenched; the head is bent backwards; and at last the whole body is stiffly arched, so as to rest upon the head and the heels. The soles of the feet are arched; the belly is hard and tense as a board; the chest is fixed, and breathing is nearly arrested. In the height of the spasm, the face looks dusky and congested, and the eyeballs stand out strongly. The jaw-muscles are also affected with spasm, and the throat is dry, with a sense of choking. Meanwhile the intellect remains quite unclouded, and the patient often expresses a sense of impending death. After the paroxysm has lasted for a minute or two, there is usually a relaxation; in this interval the patient suffers only from soreness of the muscles, but before long he experiences sensations which warn him that the fit is returning, and cries out for some one to hold him or rub his limbs. It is worthy of notice that the jaw-muscles are never so soon or so powerfully affected as in tetanus from ordinary causes. After one or two or a succession of paroxysms, respiration stops in the middle of a fit, and the heart soon after ceases to beat. The smallest dose which has produced a fatal result is half a grain; but several persons have recovered after swallowing even larger quantities, the paroxysms gradually becoming less violent, and the intervals longer. The only remarkable fact to be noted after death is the rapid or almost immediate occurrence of rigor mortis which, however, is not universal.

1 It has been erroneously stated that other alkaloids answer to this test, but Dr. Guy has very clearly proved that nothing but. strychnia produces the particular sequence of color-changes above described.

It is certain that the chief action of strychnia is exerted upon the spinal cord; the brain, in ordinary cases, does not appear to be noticeably affected. The action upon the cord produces an extremely exalted reflex irritability, through which it is, and not by direct action on the motor nerves, that the convulsions are produced. The sensory nerves are but seldom influenced, and then only in a partial and indirect manner.

Such are the phenomena of strychnia-poisoning by very large doses; sundry minor effects produced by smaller but still poisonous doses remain to be noticed. In the early days of the medicinal use of strychnia, when unwisely large doses were constantly administered, the patients were frequently thrown into a state of heightened reflex irritability, in which, though there were no absolute paroxysms, frequent twitchings of the muscles occurred, causing great discomfort and restlessness, and often rendering continuous sleep impossible. And although strychnia does not ordinarily appear to affect the brain directly, singular cerebral phenomena are occasionally induced by too large medicinal doses. The more frequent of these are greatly heightened irritability of the optic and the auditory nerves, so that brilliant light and loud sounds produce a painful impression; but in a few cases there is a true cerebral intoxication, resembling slight drunkenness. In short, though the more violent and characteristically poisonous effects of sttrychnia are due to the special action upon the cord above mentioned, it can hardly be doubted that strychnia exerts a minor influence upon every part of the nervous centres, and particularly upon the vaso-motor centres.