MICROSCOFE IX THE GARDEN. 25 



which, according to their form, are called " papillae," 

 "warts," "hairs," "glands," and "prickles." The 

 papillae are slight elevations, consisting of one, two, 

 or more cells ; the warts are larger and harder ; 

 whilst the hairs are long ; the glands contain a 

 secretion ; and the prickles are hard and sharp. 

 For examining the form and growth of these hairs, 

 the flowers of the common pansy (heart's-ease) 

 afford a good object. Some of the projections are 

 merely papillae (Fig. 70, PI. 3) ; others are found 

 longer, arid more like hairs (Fig. 71, PL 3) ; whilst 

 others are long, and as the sides of the hair have 

 contracted, they have the appearance of a knotted 

 stick (Fig. 73, PL 3). The family of grasses, wheat, 

 barley, oats, and other forms, are favourable subjects 

 for the examination of simple hairs (Fig. 69, PL 3), 

 or hairs composed of a single elongated cell. All 

 that is necessary to be done, in .order to see these 

 hairs, is to take any part of the plant where they 

 are present, and to slice off a small portion with a 

 sharp penknife or razor, and place it under the 

 Microscope. They may be either examined dry, or 

 a little water may be added, and a piece of thin 

 glass placed over them on the slide. Hairs are 

 frequently formed of several cells. On the white 

 dead-nettle the hairs are composed of two cells 

 (Fig. 74, PL 3). The nucleus, or cytoblast, is often 

 seen in these, as represented in Figs. 71, 72, and 74, 

 PL 3. On the common groundsel hairs may be 

 seen, composed of several cells, each cell containing 

 a nucleus (Fig. 75, PL 3). Hairs like a string of 

 beads are found on the pimpernel and sow-thistle 

 (Fig. 76, PL 3). Occasionally hairs become branched. 

 Thus, on the leaf of the common chrysanthemum the 

 hairs present the form of the letter T (Fig. 78, 

 PL 3). On the under-surface of the leaves of the 

 common shepherd's purse, and the bramble, hairs are 



