Some other appearances, not more conclusive, might also be mentioned here; but they belong properly to the effects of individual poisons, or of classes of poisons, not to those of poisoning generally. It may merely be remarked at present, therefore, that the appearances after death, which are really morbid, and which may be produced by poisons, are, in one great class, the signs of inflammation of the alimentary canal in its progressive stages,—in another class, the signs of congestion within the head,—and in a third, a combination of the effects of the two preceding classes; that neither set of appearances is invariably caused by the poisons which usually cause them; that congestion within the head is really seldom produced by those which are currently imagined to produce it; and that most of the appearances of both kinds are exactly similar to those left by many natural diseases. But although, on the whole, the appearances after death, when considered singly, can seldom supply evidence of poisoning even to the amount of probability, they may nevertheless prove very important under other points of view. Thus, in connection with the symptoms and the general evidence, the appearances after death may furnish decisive proof; and even should the history of the symptoms be unknown, or have been unskilfully collected, the appearances after death, by pointing out the nature of the previous illness, may furnish evidence enough to decide the case, when the moral proof is strong. Again, in cases of alleged _imputation of poisoning_ they are necessary to determine whether a poison actually found in the body was introduced during life or after death. Besides, the very absence of morbid appearances may afford presumptive proof in some circumstances,—when, for example, the question is, whether a person has died of apoplexy or of poisoning with narcotics? Farther, a few poisons, as was formerly stated, occasionally produce appearances so characteristic, as not to be capable of being confounded with the effects of any other agent whatsoever: It will be found hereafter, for example, that the mineral acids have at times left behind them in the dead body unequivocal evidence of their operation. And finally, in cases where no doubt can be entertained that poison was taken, the evidence from morbid appearances may be useful or necessary for settling whether or not it was the cause of death. Two pointed examples of this kind will be noticed under the next section.