\668 
Poison- Seer eters. 
[November, 
and this with perfect truth. But concerning these animals 
there remains very much to be ascertained. In most of 
these cases we do not know whether the poison is physio- 
logical, i.e., existing in the animal when in its normal con- 
dition, or pathological, developed only in consequence of 
some disease. Indeed when the fish, &c., are not consumed 
immediately on being taken from the sea, there is a third 
possibility, — that the poison depends on incipient decompo- 
sition, and is probably a ptomaine. 
The number of inserts which may prove very dangerous, 
if eaten, is great, — a consideration which ought to be duly 
weighed by those who recommend inserts as an article of 
human food. How many species develop cantharidine, the 
aeftive principle of the so-called Spanish fly, is far from 
having been thoroughly ascertained. An unfortunate cir- 
cumstance is that cantharides, though poisonous to all 
mammalian animals with the exception of the hedgehog, 
are eaten with impunity by frogs and several kinds of 
poultry, including, I believe, the common duck. The flesh 
of such animals becomes poisonous to man and to ordinary 
carnivorous animals. Inflammation of the bladder is not 
uncommon among French soldiers in Algeria, in consequence 
of their consuming frogs which have fed on these inserts. 
Instances are on record that poultry, including ducks, 
have been poisoned by feasting on the “ Colorado beetle ” 
( Leptinotarsa decemlineata), and by some kinds of caterpillars 
not properly identified. It is, indeed, very probable that 
caterpillars feeding upon poisonous plants will prove deadly. 
Such caterpillars are generally very conspicuously coloured, 
as if in warning. 
We have now to consider the question, Of what use are 
defensive poisons either to plants or to animals ? It is con- 
tended that the death of the devourer can be of no benefit 
to the plant or animal devoured, and will not serve as a 
protection to others of the same species, since dead birds 
and dead inseCts, like dead men, tell no tales. 
But against this argument we may set the indisputable faCt 
that unwholesome plants, inserts, &c., are very generally 
avoided by such species as would otherwise be likely to prey 
upon them. It by no means follows that a fatal dose will 
always be taken. Differences in the quantity consumed, in 
the'previous state of the stomach, as full or empty, and in 
the constitution of the eater, cannot fail to make themselves 
felt. He may come off with an illness, more or less severe, 
but not fatal, and will in future shun the cause of his 
sufferings. In whatever way it may be effected, such 
