It has been customary with authors to call all those cases of tetanus, which are not brought on by wounds, symptomatic. They are no more so than those which are said to be idiopathic. They all depend alike upon irritating impressions, made upon one part of the body, producing morbid excitement, or disease in another. It is immaterial, whether the impression be made upon the intestines by a worm, upon the ear by an ungrateful noise, upon the mind by a strong emotion, or upon the sole of the foot by a nail; it is alike communicated to the muscles, which, from their previous debility and irritability, are thrown into commotions by it. In yielding to the impression of irritants, they follow in their contractions the order of their predisposing debility. The muscles which move the lower jaw are affected more early, and more obstinately than any of the other external muscles of the body, only because they are more constantly in a relaxed, or idle state. The negroes in the West-Indies are more subject to this disease than white people. This has been ascribed to the greater irritability of their muscular systems, which constitutes a part of its predisposing cause. It is remarkable that their sensibility lessens with the increase of their irritability; and hence, Dr. Moseley says, they bear surgical operations much better than white people. New-born infants are often affected by this disease in the West-Indies. I have seen a few cases of it in Philadelphia. It is known by the name of the jaw-fall. Its causes are: 1. The cutting of the navel string. This is often done with a pair of dull scissors, by which means the cord is bruised. 2. The acrimony of the meconium retained in the bowels. 3. Cold air acting upon the body, after it has been heated by the air of a hot room. 4. Smoke is supposed to excite it, in the negro quarters in the West-Indies. It is unknown, Dr. Winterbottom informs us, among the native Africans in the neighbourhood of Sierra Leone. I am aware that it is ascribed by many physicians to only one of the above causes; but I see no reason why it should not be induced by more than one cause in infants, when we see it brought on by so many different causes in grown people. The tetanus is not confined to the human species. It often affects horses in the West-Indies. I have seen several cases of it in Philadelphia. The want of uniform success in the treatment of this disease, has long been a subject of regret among physicians. It may be ascribed to the use of the same remedies, without any respect to the nature of the causes which produce it, and to an undue reliance upon some one remedy, under a belief of its specific efficacy. Opium has been considered as its antidote, without recollecting that it was one only, of a numerous class of medicines, that are all alike useful in it.