28 



DESCRIPTIVE BOTANY. 



several united (fig. 19.). In some, the vesicles are 

 rigid, elongated, and sharp spicule ; in others they 



constitute a globular mass of a glandular structure 

 (fig. 20.), and secrete various juices of glutinous, 



sweet, acrid, and other properties. Stings are sharp, 

 pointed hollow bristles, perforated at the extremity, and 

 seated on a glandular mass of cellular tissue which 

 secretes the poison (fig. 20. a). When the hand is 

 gently pressed against them, the delicate point pene- 

 trates some pore of the skin, at the same time the 

 bristle is forced against the gland at its base, and the 

 poison rises into the tube in a manner strictly analogous 

 to that by which a discharge of venom is effected from 



