ON THE MEDICAL EVIDENCE REQUIRED TO SUBSTANTIATE AN ACCUSATION OF
POISONING.
Although the phenomena by which we are enabled to discover the
administration of poison, will be fully enumerated, and carefully
examined, under the history of each particular substance, and will
necessarily vary according to the chemical properties, and physiological
action of each individual poison; yet there are some general points of
evidence, and several questions of importance, upon which it is very
essential to arrive at some definite conclusion, some fixed
understanding, before we proceed to the consideration of the particular
details, and subordinate ramifications, of this complicated subject.
The great constituents which form the medical proof of poisoning, are
derived from Chemical, Anatomical, and Pathological researches; viz.—the
existence of poison in the stomach or intestines; the morbid
appearances, corresponding to such poison, upon dissection; and the
characteristic symptoms which accompanied the action of it, previous to
death. Where these circumstances occur in combination, the demonstration
may be said to be complete, for we have arrived at absolute certainty.
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?_
It must be admitted that the symptoms produced by violent irritation in
the primæ viæ, are not characterised by a diversity, corresponding with
that of the causes which may excite it; thus it is, that we have a
disease to which the term “_cholera_” has been assigned, and which is
indicated by the following symptoms, “_Humoris biliosi vomitus, ejusdem
simul dejectio frequens; anxietas; tormina; surarum spasmata_,” (Cullen
Syn: LX. 1.) symptoms which supervene, and with nearly the same force,
the spontaneous effusion of acrid bile into the intestines, and the
ingestion of some acrid poison; and hence the nosologist has very
properly divided _cholera_ into two species, viz.