SINCE reading this paper we have met with an elaborate 
monograph by Gravis, on the Anatomy of Uriica (Mem. 
Acad. Roy. de Brux. t. alvii. pp. 1—256). He dis- 
tinguishes three types of hair, ‘ poils glanduliferes,’ ‘ poils 
piquants’ and ‘ poils urticants,’ but does not go into the 
physiological action of their contents. 
