24 COMPOUND ORGANS OP PLANTS. 



vegetable world ; and not without reason, for there is a 

 remarkable similarity in structure between the poison teeth of 

 the latter and the glandular hairs of the former. In both the 

 apparatus is tubular, and the pressure of the hair or tooth on 

 the poison gland ejects the poison into the system. 



The poison of nettles in temperate climates is not of 

 much consequence, but as we approach warmer regions sting- 

 ing nettles become more numerous and deadly. " Every 

 person is acquainted with the sting of the common nettle, 

 Urtica urens, but no notion can be formed from it of the 

 torture which its allies, Urtica stimulans, Urtica crenulata, 

 produce in the East Indies. A gentle touch is sufficient to 

 make 4he limb swell up with the most fearful rapidity, and the 

 suffering lasts for weeks ; nay, one species, growing in Timor, 

 Urtica urentissima, is called by the natives Daun setan, 

 DeviFs Leaf, because the pain lasts for years, and sometimes 

 death itself can only be avoided by the amputation of the 

 injured limb."* 



When the hairs of the epidermis are hardened by deposits, 

 as in the rose and blackberry, they are called prickles, (aculei). 

 In their youth, they completely resemble hairs, and are 

 dispersed without order on the stem and leaves, but with 

 age they become thickened, elongated and indurated, as may 

 be seen on the rose, where they present themselves in every 

 stage of development. 



Hairs are sometimes attached to seeds for the purpose of 

 scattering them, as in the cotton plant. In Rhus cotinus, or 

 the wig tree, the flower .stalks are changed into hairs. 



* Dr. Schleiden. 



