In the present day every one allows that poisons may become absorbed, and that, provided they produce poisonous effects at all, they are absorbed, in whatever way they may have been applied to the body. But it is sometimes asked, Is this absorption necessary for their action? The following evidence may be briefly noticed as in some degree affording an affirmative answer to this question. Magendie divided all the parts of one of the posterior extremities of a dog, the artery and vein being reconnected by quills, so as to preclude the possibility of the effects being conveyed by the nervous filaments supplying the coats of the vessels; on applying a portion of upas tieuté to a wound in the foot, the symptoms of poisoning occurred, and death took place in ten minutes. If the veins leading from a poisoned part be tied, the arterial and nervous communication being complete, the symptoms of poisoning do not occur. Mr. Blake introduced some prussic acid into the stomach of a dog, through an opening in its parietes, after he had ligatured the vessel entering the liver (the vena portæ, which, directly or indirectly, receives the gastric veins); no effect ensued until the removal of the ligature, within one minute of which proceeding the poison began to act. And lastly, not only has prussic acid been discovered in the blood of an animal which perished in thirty-five seconds, but in some experiments made by Mr. Erichsen, in a case of extroversion of the bladder, prussiate of potass was found in the urine within one minute of its being swallowed on an empty stomach. The chief argument in favor of a _sympathetic_ or direct nerve action, is the almost instantaneous manner in which some poisons act; fatal effects occurring, it is said, before sufficient time has elapsed to allow of absorption. It has, however, been proved that the round of the circulation may be accomplished much more speedily than has been imagined. Thus, the ferrocyanide of potassium injected into the jugular vein of a horse was discovered throughout the entire venous system in twenty-seconds; and Mr. Blake has inferred from his experiments that a poison may be diffused through the body in nine seconds. It may therefore be concluded that in most instances poisons act by being absorbed and conveyed with the blood to the different organs which they impair, or the nerve centres which rule the functions of these; some paralyzing the heart when they reach it, some affecting the brain or the spinal cord, some stopping the play of the lungs and others acting upon the different glands. Nevertheless, in view of the extreme rapidity with which death is brought about in a few instances, the possibility of a direct shock to the nervous system causing death must not be overlooked. The action of a poison may be variously modified, and the modifying circumstances must be carefully taken into consideration in the formation of a prognosis and in suggesting a line of treatment.