symptoms, such as giddiness, headache, ringing in the ears, depraved
vision, or partial palsy. But it is an error to suppose that warning
symptoms always occur; nay, if we may trust the experience of M.
Rochoux, they are by no means common: of sixty-three cases which came
under his notice nine only had distinct precursory symptoms.[1625]
Poisoning with narcotics of course has not any precursory symptom except
by fortuitous combination. And consequently, if warning symptoms have
occurred, the presumption is, that the cause of death is a natural one.