CHAPTER I 



at 9 are repeated in various parts of the figure, more particularly next to the epider- 

 mis of the lower surface. 



" i, a set of so-called motor cells, in this instance composed of two cells, whose 

 nuclei are pointed out at 2 and 3 ; 4, an internal cell of somewhat similar character 

 to that pointed out at i, 2, and 3 ; 5, another cell of the same class cut in such a 

 way that the nucleus has been removed ; 6, sclerenchymatous cells imparting 

 strength to the nbro-vascular bundle ; 7, one of the layer of parenchymatous cells 

 rich in chloroplasts and immediately surrounding each fibro-vascular bundle ; 8, one 

 of the stomata, found more rarely on the upper than on the lower surface of the 

 leaf ; 9, woody cells imparting strength to the cane leaf, and occurring on the dorsal 

 and ventral side of each nbro-vascular bundle ; 10, one of the cells constituting the 

 sheath of the vascular bundle these cells contain chloroplasts arranged along the 

 outsides of their walls; n, tracheal vessel; 12, one of the cells of the upper 

 epidermis ; 13, nucleus of a similar cell ; 14, upper cuticle at its usual thickness ; 

 15, a two-celled hair on the surface of the leaf ; 16, thinner cuticle of the upper 

 surface of the leaf as it occurs over the so-called motor cells ; 17-18, group of 

 so-called motor cells, consisting in this case of four cells ; 19, nbro-vascular bundle 

 of intermediate size ; 20, chloroplast in one of the cells of the lower epidermis ; 

 21, one of the stomatic openings that are abundant on the lower surface of the leaf ; 



FIG. 5 



this one is closed an open one may be seen at 25-26 ; 22, accessory (?) cell of the 

 stomatic opening ; 23, one of the smallest fibro-vascular bundles ; 24, one of a group 

 of cells very rich in protoplasm, which extends between the vascular bundles the 

 nearer these cells are to the lower epidermis the denser their protoplasmic contents ; 

 25-26, protoplasts in the guard cells of the stomatic opening ; 27, one of the sieve 

 tubes among these sieve tubes may be seen the smaller companion cells and their 

 protoplasts ; 28, extra chlorophyll-bearing cells outside the single layer surrounding 

 the vascular bundle ; 29, lip of one of the stomatic guard cells ; 30, cell rich in 

 protoplasm, of the same class as 24 ; 31, nucleus of one of the companion (?) guard 

 cells ; 32, fibro-vascular bundle of small size ; 33, apparently a locule in the 

 thickened portion of the wall of the stomatic guard cell ; 34, entrance between the 

 guard cells of the stomatic opening ; 35, cuticle of the lower surface of the leaf ; 

 36, fibro-vascular bundle of intermediate size ; 37, 37, 37, air chambers immediately 

 above the stomatic openings. Throughout the illustration the nuclei are shown 

 grey, and the nucleoli black. The tissue represented at 24 and 30 is probably 

 primary leaf-tissue, from which during the growth of the leaf the various tissues 

 represented have been differentiated." 



In Figs. 5 and 6 are shown, after Dickoff, 3 the upper and under side of 

 the leaf highly magnified, the legend being as under : /, long cell ; kz, silica 

 cell ; kr, cork tissue cell ; km, stoma ; be, air cell ; h, hair ; st t spine. 



