MACROSCOPIC AND MICROSCOPIC CHARACTERS OF PLANTS. 



801 



TABLE J 24. Number of stomala on lower epidermis in a field. 



Transverse sections of the leaf, near the apex, were 

 examined in the region of the midrib (Plate 31, figs. 187, 

 188, and 189). The upper epidermis consists of rounded 

 cells with a thick cuticle on the outer face. The upper 

 epidermis is slightly deeper in C. eburneum than in 

 C. lowianum, and deeper in the hybrid than in either 

 parent. The lower epidermis also consists of rounded 

 cells with a thick cuticle on their outer face but smaller 

 than the upper epidermal cells. The lower epidermis is 

 deeper in C. lowianum than in C. eburneum and in the 

 hybrid, though between the two, it is nearer the depth of 

 C. lowianum. (Table J25.) 



The cells of the layer beneath the upper epidermis, 

 the aqueous-tissue, become greatly elongated in the re- 

 gion of the midrib. They are less deep and wider in 

 C. lowianum than in C. eburneum, and deeper in the 

 hybrid than in either parent and of the same width as 

 C. lowianum. (Table J 25.) 



The midrib bundle is much larger in C. lowianum 

 than in C. eburneum, and in the hybrid not quite as deep 

 as in C. eburneum. The width in the hybrid is identical 

 with that of C. eburneum. The diameter of the largest 

 vasa of the hybrid is also identical with that of C. ebur- 

 neum. (Table J 25.) 



TABLE J 25. 



The resemblance, on the whole, in these transverse 

 sections of the leaf near the apex to C. eburneum is much 

 greater than to C. lowianum. This relationship is also 

 shown in transverse sections taken at the middle of the 

 leaf, at which point the depth of the lower epidermis and 



the depth and width of the midrib are in the hybrid iden- 

 tical with C. eburneum. The diameter of the largest 

 vasa in the hybrid is nearer C. eburneum than C. lowi- 

 anum. Only the depth of the upper epidermis is identical 

 with C. lowianum and the size of the cells of the layer 

 beneath the upper epidermis is more like that of C. 

 lowianum than of C. eburneum. (Table J 25.) 



Transverse sections near the apex were also examined 

 at a point midway between the midrib and the margin. 

 The upper epidermis appears as a layer of rounded oval 

 cells with a thick cuticle on the outer face. It is deeper 

 in C. eburneum than in C. lowianum, and exactly mid- 

 intermediate in the hybrid. The lower epidermal cells are 

 oval with a much thicker cuticle on the outer face. 

 These are much deeper in C. eburneum than in C. lowi- 

 anum, and though between the two parents in depth in 

 the hybrid, yet nearer C. eburneum. 



Between the two layers of epidermis are layers of 

 rounded oval cells rather closely packed together and 

 very well filled with green chloroplasts. The layer just 

 beneath the upper epidermis, the aqueous-tissue, is com- 

 posed of slightly larger cells which do not contain many 

 chloroplasts. There are 12 layers of cells in the meso- 

 phyll of C. lowianum, 10 in C. eburneum, and 10 in 

 the hybrid. 



Kunning parallel with the midrib and just beneath 

 the upper epidermis and lower epidermis are strands of 

 heavily thickened sclerenchyma. Those beneath the 

 upper epidermis are much larger than those beneath the 

 lower epidermis. Those beneath the upper epidermis 

 are practically circular in C. lowianum; deeper than wide 

 in C. eburneum; and circular in the hybrid. They are 

 smaller in the hybrid than in either parent, though of 

 the same width as in C. eburneum. They are more 

 numerous in C. eburneum than in C. lowianum, and in 

 the hybrid of the same number as in C. lowianum. (Table 

 J26.) 



TABLE J 26. 



The sclerenchyma strands near the lower epidermis 

 are also circular in C. lowianum; deeper than wide in C. 

 eburneum; and circular in the hybrid. They are smaller 

 in the hybrid than in either parent. They are more 

 numerous in C. eburneum than in C. lowianum; but 

 between the parents in number in the hybrid, though 

 nearer C. lowianum. (Table J 26.) 



FLO WEB. 



The upper epidermis of the dorsal sepal in all three 

 plants were examined at the middle point. The cells 

 are pentagonal or hexagonal and have rather thick walls. 

 They are larger in C. lowianum than in C. eburneum, 

 and shorter in the hybrid than in either parent, but be- 



