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 



