6yo 
Poison-Secreters. 
[November, 
under the shade of the yew-tree. But here, and still 
more in the case of the Hippomane mancinella of Cuba, 
and of certain other tropical trees, further investigation is 
needed. 
Among animals an intermediate position seems to be taken 
by the venomous hairs of many caterpillars, which contain 
and emit formic acid in a very concentrated form. A bird 
or other animal seeking to make a prey of such caterpillars 
is almost certain to receive envenomed wounds. But the 
hairs become detached as the caterpillar creeps about, and 
are carried away by the wind. The nests of some of 
these species should be approached from the leeward side, 
or they may pioduce painful inflammations on the face, 
and if carried into the lungs they may prove fatal. Cer- 
tain oak-woods in France and Germany are shunned by 
the country people during summer, on account of these 
inserts. 
As a further stage in the direction of offensiveness, we 
may note the projection of noisome or corrosive secretions 
to some distance. Thus the “ bombardier beetles ” ( Brachini ) 
emit an acid vapour or highly volatile liquid, which instantly 
evaporates, accompanied by a faint explosion. Cychrus 
rostratus projects a drop of concentrated formic acid to the 
distance of some inches. If this liquid touches the face it 
causes a painful blister. 
Passing over a number of inseCts which if handled or 
alarmed emit liquids of unknown composition, we come to 
the skunk. The abominable secretion which this creature 
projects if annoyed may fairly rank among poisons, since it 
produces violent sickness if the fume is inhaled, and since a 
drop, entering the eye of a dog, has been known to produce 
blindness. 
But we must now hasten to those creatures which can 
employ their poisonous secretions as the means of offence 
by the instrumentality of special organs. 
Among these we find only one group of plants,— the 
nettles. If touched they sting, by conveying through their 
hollow hairs minute drops of formic acid. Such is, at least, 
the poison present in the common nettle of Europe ; but 
some more potent poison — perhaps a homologue of formic 
acid not yet examined — must be present in certain tropical 
species. The effects of Urtica urentissima, of Timor, may 
last for months, and may terminate fatally. The “ devil’s 
leaf,” of Ceylon, has produced almost instantaneous 
death, whilst an Australian nettle, about which exaCt in- 
formation is lacking, is said to be rapidly fatal to horses, 
