Thistles and Nettles 329 
without this defence the toothed leaves would rend 
clothing to ribbons, and cruelly tear the flesh be- 
neath. In the saw-palmetto of the Florida “ flat- 
woods,’’ every leaf-stem is protected on both sides 
with curving points like the teeth of a saw. 
The stings of our nettles are decidedly unpleas- 
ant, but they are not to be compared for a mo- 
ment to the sufferings which can be inflicted by 
some tropical species. Listen, for instance, to De 
La Tour’s experiences with an East Indian nettle. 
“One of the leaves,’’ he says, ‘‘ slightly touched 
my hand. At the time I experienced a slight 
pricking. The pain increased. In an hour it had 
become intolerable, as if some one was rubbing my 
hand with a red-hot iron. The pain spread rapidly 
along my arm as far as the armpit. I did not 
finally lose the pain for nine days.”’ 
. Even our comparatively innocent nettle has one 
of the most highly developed of all the devices by 
which familiar plants guard themselves against the 
attacks of animals. Its sting is a tiny hollow cone, 
with the point upward. At the base of this are 
a number of cells filled with an irritating fluid con- 
taining formic acid, the same poison which gives 
virulence to the bites of the ant and the spider. 
And at the tip of the cone is a small round disk 
