LEAF OF FAGUS. 



195 



leaf, all in the same direction, packed together, as already sug- 

 gested, and cut between elder- or sunflower-pith ; in which way 

 not only more but thinner sections can be obtained. Another 

 favourable leaf for cutting, owing to its comparative stiffness, 

 is that of the Australian blue-gum tree (Eucalyptus globulus), 

 and this may, with advantage, replace Ruta. It is provided with 

 oil glands of a similar character, and the tufted arrangement 

 of the palisade cells is exceedingly well marked. 



Leaf of Fagus sylvatica. As a second object for study we 

 select the leaf of the Beech, Fagus syhatica. The delicate 

 texture of the leaf makes a thin section in this case less easy 

 to obtain, and it will be well to again place straight narrow 



FIG. 77. Cross-section through the leaf of Fagus sylvatica. ep, epidermis ; pi. 

 palisade parenchyma ; sp' and sp", spongy parenchyma ; sp' collecting cells ; k, 

 crystallogenous cells, in k', a cluster-crystal ; st, stoma (x 360). 



strips of the leaf between the two pieces of elder-pith, or, to pack 

 together several of such strips, and then place them between the 

 pieces of pith. Stomata are found on the epidermis of the under 

 side only. Adjoining the epidermis of the upper side (ep, Fig. 77) 

 in somewhat fan-like groups of cells, is a layer of elongated 

 palisade cells (pi). These palisade cells are again more or less 

 completely separated from one another by intercellular spaces. 

 At their lower ends they bend together inio bunches, and to each 

 bunch is joined one or several funnel-shaped, broadened cells of 

 the spongy parenchyma (sp). These latter are connected with 

 the elongated cells of the spongy parenchyma into a loose net- 

 work, which extends to the epidermis of the under side (ep"). 

 Single cells, devoid of chlorophyll, but with a cluster-crystal 



