THE PRINCIPLES OF BOTANY. 
339 
still used as food by a large number of people ; the species 
of caladium and colocasia, under the names of eddoes and 
yams, are well known in the West Indies ; we have eaten 
both eddoes and yams roasted like potatoes, and found them 
to be exceedingly good. 
The foliage of most of the order possesses highly irritant 
properties. Our country children frequently get sore noses 
and swollen faces from rubbing these parts with hands that 
had previously been busy with lords and ladies. Professor 
Lindley tells us that “ the spadices of some species have a fetid 
putrid smell, others, such as Arum cordifolium, italicum, and 
maculatum, are found to disengage a sensible quantity of 
heat at the time when they begin to expand. The emana- 
tions from Arum dracunculus are extremely inconvenient; 
when in flower they produce a dizziness, headache, and 
vomiting. A writer in the Annals of Chemistry says that he 
was attacked with violent headache and sickness after 
gathering about forty of the spadices.” There can be no 
doubt but that the arads form a very active group of plants, 
but it would appear that in most, if not in all cases the active 
principles are dissipated by heat, and hence even the corms 
or tubers, which in the raw state would be, if not poisonous, 
at least acrid and disagreeable, become wholesome and 
agreeable esculents when cooked. 
The palms, which next claim our attention, are amongst 
the most useful family of plants the world possesses. “ Wine, 
oil, wax, flour, sugar, salt,” says Humboldt, “ are the produce 
of this tribe, to which von Martius adds thread, utensils, 
weapons, food, and habitations.”* 
It would take too long to go into a detail of the economic 
or medicinal qualities attributed to this tribe of plants, but 
we may mention palm-nut oil as a useful product both to the 
pharmacien and the machinist. Cocoa-nut oil is also used in 
considerable qualities. 
Dragons’ blood is procured from the fruit of Calamus draco. 
This dark red resin was once used to colour tinctures, and 
the cow leech has still faith in it as a reddening ingredient in 
drinks for red water ; so our grandmothers still hold the 
yellow bark of the barberry tree as “ a sovereign remedy 
for jandersf and a dairyman would consider any drench for 
yellows as quite inoperative that did not contain turmeric. 
It was upon this doctrine of signatures which our forefathers 
acted in their uses of vegetables, but, as in the present day, 
educated men seek for principles. Dragons’ blood, which 
* Vegetable Kingdom. 
