92 



VII. TBICHOMES WAX. 



also, that the chlorophyll-containing cells of the tissue of the leaf 

 join radially, and without gaps, with the somewhat broadened 

 part of the foot projecting below the epidermis. 



Hairs of Matthiola. The hairs of the ten-week stock, Mat- 

 thiola annua (Fig. 33, C), are repeatedly branched in one plane 

 parallel to the leaf surface. These hairs, especially on the under 

 surface of the leaf, are set so closely together that their branches 

 interlace. The cavity of the hair, in consequence of the strong 

 thickening of the walls, is well-nigh obliterated. Knobs are 

 scarcely at all developed on the surface. 

 The view of the epidermis from the inner 

 side (by means of surf ace- sections placed 

 upside down) is very instructive, for it 

 shows a tolerably marked swelling of the 

 globular foot of the hair, and around it an 

 exceedingly beautiful radial arrangement 

 of the chlorophyll-containing cells. 



Hairs of Pansy. In the groove which 

 leads to the spur-like elongation of the 

 lower or anterior petal of the pansy ( Viola 

 tricolor) are very peculiar long unicellular 

 hairs (Fig. 34). They can be seen very 

 well if a cross-section of the lower petal is 

 taken near the place where the tubular 

 spur opens out into the furrow or groove. 

 Each of certain epidermal cells grows out, 

 almost in its entire width, into a hair. 

 This is covered with irregular gnarled 

 swellings. The cuticle of the hair shows 

 slight longitudinal ridges. The cell-sap 

 is colourless, but yellow pigment-bodies 

 (chromatophores) are often present in the protoplasmic sac. 



Staminal Hairs of Mullein. The staminal filaments in the 

 flowers of the common Mullein (Verbascum nigru?n) are covered 

 with unicellular violet hairs. In order to examine them the 

 anther should be removed from the filament, and this latter 

 pulled to pieces with needles in a drop of water on an object- 

 slide. The hairs are very long, swollen out at the end into the 

 form of a club, and with violet cell-sap. The surface of the hair 

 is covered with somewhat elongated protuberances which ascend 

 in more or less regular spirals. 



FIG. 34. Hairs from t 

 i'urrow of the lower petal 



