THE MICROSCOPE. 



59 



and is wooly on close inspection. The wooliness is caused by the 

 presence of numerous long, slender and empty hairs (see a, fig. 2). 

 The hairs are of an unusual length and thickly covered with minute 

 projections of cellulose. 



There are only a few hairs found on the upper surface of the 

 leaf. They are much shorter, broader and only faintly marked with 

 projections. (See />, fig. 2.) 



Fig. 3. Leaflet of Caroba. Cross Section. «, Cuticle. .'■, Epidermal Cells, c. Palisade 

 Cells, c, Lower Epidermis. /", Oil Drops. //. Epidermal Glands, x 500 diameters. 



There are in addition to these hairs some beautiful glands 

 thickly scattered over the leaf surface (see c, fig. 2). These are 

 wheel-shaped, and composed of eight or ten cells. in the dried 

 leaf they are of a reddish brown color, and probably contain oil and 

 some of the essential properties of the leaf. Similar glands are 

 found on the surface of a few other kinds of leaves, and they gen- 

 erally contain "secreted resinous, gummy or other substances."* 



The cross sections of this leaflet gives the usual leaf structure 

 (see fig. 3). A thick cuticle protects the leaf on the upper surface 

 (a). The epidermal cells (l>) are unusually large. Directly beneath 

 these are the long slender palisade cells, filled, when fresh, with 

 bright green chlorophyll; but in its dried condition filled only with 

 dead brown chlorophyll bodies. The lower half of the leaf is com- 

 posed of the usual loosely packed parenchyma (d) with occasionally 



''See Bessy's Botany, p. 96. 



