and its Alkaloid Conia. 397 
mited in number ; few are minutely described ; several occurred 
before physicians had learned to discriminate accurately the exter- 
nal characters of the true hemlock, and other poisonous umbelli- 
ferous plants resembling it; in scarcely any of them is allusion 
made to the risk of error from this cause, or any pains taken to 
establish the identity of the poison ; and in some, including one 
related by myself, which occurred twelve years ago, the symptoms 
were taken at second hand, the individuals having died before 
being seen by a competent observer.* The resemblance subsist- 
ing between hemlock and various umbelliferous plants, such as 
Cicuta virosa, Althusa cynapium, Ginanthe crocata, Cherophyllum 
temulentum, is alone sufficient to vitiate most of the modern de- 
scriptions of the poisonous effects of the first species. We know 
that they often have been confounded together ; and hence we 
can have no certainty what the plant was in special cases of poi- 
soning, where the name merely is given, and the narrative does 
not contain internal evidence of its exact nature. Singular then 
as it may appear, we are very imperfectly acquainted with the 
real effects of one of our most familiar poisons on the human 
body. 
For the like reasons, our knowledge of the effects of hemlock 
on the lower animals is far from being precise or positive. The 
only unequivocal experiments, indeed, are those of Professor Or- 
FILA,} and a few performed by Professor Scuusartu ;{ and from 
these we should infer, that, besides possessing irritant properties, 
hemlock induces giddiness, convulsions, loss of sensibility, palsy, 
and coma. This account does not agree with the account given 
above of the action of conia, which does not seem to affect the 
senses so long as the respiration goes on. But it is possible that 
the difference is more apparent than real, and that hemlock has 
* Gmelin’s Pflanzengifte 605. Corvisari’s Journal de Médecine, xxix. 107. Philo- 
sophical Transactions, xliii. 18. Wbmer, ut supra, i. 171. My Treatise on Poisons, 
} Toxicologie Générale, ii. 303. 
t Horn’s Archiv fiir Medizinische Erfahrung, 1824. 
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