But scientific evidence, short of such perfection, may be amply sufficient to lead to conviction. The fact of a poison having been found in the body may supersede the necessity of pathological testimony: thus _Hoffman_,[153] “_Si venenum adhuc intra ventriculum reperitur, res est clarissima, ubi vero, illud haud deprehenditur, res adhuc dubii plena est._” We shall hereafter find that the discovery of organic lesions, without the chemical proof (“_experimentum crucis_[154]”) is often vague, and seldom satisfactory, and that even when sanctioned by the testimony of the pathologist, will frequently be deemed insufficient to sustain an indictment, unless indeed it be collaterally supported by a very strong chain of circumstantial evidence of a moral nature, especially such as relates to the character, conduct, and presumed object of the prisoner. As the duty of the medical witness, upon such occasions, must always be anxious, and generally perplexing, it becomes our duty at least to clear away those adventitious difficulties with which ignorance on the one hand, and sophistry on the other, have obstructed a path of inquiry, which, from its very nature and direction, must necessarily be obscure and intricate. We shall endeavour upon this, as we have upon similar occasions, to bring the more leading and popular points of controversy within the scope of a few prominent questions, assigning to each a share of attention, commensurate with our idea of its importance. Q. 1. _Whether all, or most of the symptoms, characteristic of the action of corrosive and narcotic poisons, may not arise from morbid causes of spontaneous origin?_ Q. 2. _Whether organic lesions, similar to those produced by poisoning, may not occasionally result from natural causes?_ Q. 3. _Whether the rapid progress of putrefaction, in the body generally, or in any particular part, is to be considered as affording any presumptive evidence, in favour of a suspicion of poisoning?_ Q. 4. _How far the absence of poison, or the inability of the chemist to detect it, in the body, or in the fluids ejected from it, is to be considered as a negative to an accusation of poisoning?_ Q. 5. _What degree of information can be derived from administering the contents of the stomach of a person supposed to have been poisoned, to dogs, or other inferior animals?_ We shall now consider these questions in succession. Q. 1. _Whether all, or most of the symptoms, characteristic of the action of corrosive and narcotic poisons, may not arise from morbid causes of spontaneous origin?_