102 



HARDVvICKE'S SCIENCE-GOSSIP. 



[May 1, 1868. 



imity to each other. The flower of the. Snapdragon 

 has single-celled hairs, some terminating in a globu- 

 lar gland, others in a cone-shaped gland. The 

 garden verbena has some hairs like a flattened 

 rosette on the top of a tall stalk, and others 

 breaking out on all sides of their entire length in 

 curiously knotted excrescences. The hair of the 

 Marigold consists of a double layer of elongated 



Fig. 75. Hair of Tobacco. Fij. 76. Hairs of Verbena. 



Fig. 77. 

 Stinging Hair of Nettle. 



Fig. 78. 

 Hairs of Snapdragon. 



Fig. 79. Hair of Ivy. 



Fig. 80. Hair of Hollyhock. 



cells, built up one upon another, and lying closely 

 side by side. The base of the hair of the common 

 Stinging-nettle contains an irritating secretion, 

 which flows through the straight tubular elongation 

 till it reaches the little bulb-like swelling at the 

 extremity of the hair. This is easily broken off 

 when touched by any object, and the acrid fluid then 

 escapes and produces the well-known sting. 



Some hairs are forked or branched, like those of 

 the Dandelion and the Plane-tree ; others consist 

 of a single elongated cell, like that of the Cabbage. 

 In the hair of Marvel of Peru the elongation is 



Fig. 83. 

 Hair of Marigold. 



Fig. 81. 

 Hair of Thistle. 



Fig. 8-2. 

 Hair of Grouiulsel. 



Fig. 84. 

 Hair of Lobelia. 



formed by a chain of cells placed end to end, and 

 connected by slender threads. In the Thistle and 



Fig. 85. Hair of Da delion. 



Fig. 86. Hair of Arabis. 



the Groundsel, the last cell of the hair is lengthened 

 out to a bristle-like extremity. On the leaves of 

 some Geraniums may be found two kinds of hairs, 



