MACROSCOPIC AND MICROSCOPIC CHARACTERS OF PLANTS. 



809 



pale-lavender sap in the cells of the layer beneath the 

 epidermis, and also to yellowish-green chromoplasts in 

 the epidermal cells and hairs. 



Sections of the inner (upper) epidermis of the label- 

 lum over the colored concave area were compared. This 

 area is greenish yellow in D. findlayanum ; deep reddish 

 violet in D. nobile; and deep reddish violet in the hybrid, 

 but with less red than in D. nobile. Long multicellular 

 hairs are very numerous. They are much shorter in D. 

 findlayanum than in D. nobile, and in the hybrid, while 

 between those of the parents, the average length is much 

 nearer D. nobile than D. findlayanum. (Table J 41.) 



TABLET J41. 



The greenish-yellow color in D. findlayanum is due to 

 the presence of yellow chromoplasts in both epidermal 

 cells and multicellular hair cells. The deep reddish- 

 violet color in D. nobile is due to the cells and multi- 

 cellular hairs being filled with a reddish-violet cell sap. 

 Colorless plastids are also present. The deep reddish- 

 violet color in the hybrid (less red than in D. nobile) is 

 due to the presence of a deep crimson, with a touch of 

 violet cell sap in the cells and hairs, and also greenish- 

 yellow chromoplasts. The colored plastids appear to give 

 the slightly different shade between D. nobile and the 

 hybrid. The hybrid thus has inherited greenish-yellow 

 chromoplasts from one parent, and a reddish-violet cell 

 sap from the other. 

 28 



Above, the wide concave part the labellum broadens 

 out and bends slightly downward, forming a rim. Sec- 

 tions of the upper epidermis above this rim were com- 

 pared. This area was found to be covered with numerous 

 multicellular hairs containing yellow chromoplasts. 

 These hairs are much shorter in D. findlayanum than in 

 D. nobile, and in the hybrid while between those of the 

 parents the average length is much nearer that of D. 

 findlayanum than of D. nobile. (Table J 41.) 



The color in D. findlayanum and D. nobile is pale 

 yellow, due to small pale-yellow chromoplasts in the cells 

 and hairs. In the hybrid, however, the rim is sulphur- 

 yellow, the chromoplasts being of a darker yellow than in 

 either parent. 



Sections of the upper epidermis of the labellum over 

 the reddish-violet apex were also examined. The cells 

 are longer and wider in D. findlayanum than in D. nobile. 

 In the hybrid they are longer than in either parent, and 

 in width between those of the parents but much nearer to 

 D. findlayanum. (Table J 41.) 



Multicellular hairs are absent in D. findlayanum. 

 They are rather numerous in D. nobile, and only a little 

 less numerous in the hybrid. The hairs are longer in 

 D. nobile than in the hybrid. (Table J 41.) 



In D. findlayanum the color of the apical area is a 

 pale red-violet due to a pale reddish-violet sap in the 

 layer of cells beneath the epidermis. Colorless plastids 

 are present in the epidermal cells. In D. nobile, the 

 color is the same as in D. findlayanum, and also due to a 

 pale reddish-violet sap in the layer of cells beneath the 

 epidermis. Colorless or very pale greenish-yellow plastids 

 are present in the epidermal cells and hairs. In the 

 hybrid the color is of a deeper red-violet than in either 

 parent, and is due to a deeper red-violet sap in the layer 

 of cells beneath the epidermis. Colorless or very pale 

 greenish-yellow plastids are present in the epidermal cells 

 and hairs. 



COMPARATIVE SUMMARY OF THE CHARACTERS OF THE 



HYBRID DENDROBIUM CYBELE AND ITS 



PARENT-STOCKS. 



The hybrid was found to be : 



(1) The same or practically the same as the seed 

 parent: In the smoothness of the external tubular part 

 of the labellum; depth of the bundle on the transverse 

 section of the third internode; width of the upper epi- 

 dermal cells at the top of the petiole; length of the 

 lower epidermal cells of the petal. 



(2) The same or practically the same as the pollen 

 parent: In the diameter of the swellings of the stem at 

 the nodes; width of the lamina; color of the external 

 tubular part of the labellum ; color of the internal tubu- 

 lar part of the labellum; (6) diameter of the largest 

 vessels in the transverse section of the root; size of 

 the intercellular spaces and number of bundles in the 

 transverse section of the third internode of the stem; 

 width of the upper epidermal cells of the leaf at the 

 base ; length of the upper epidermal cells at the top of the 

 petiole; width of the upper epidermal cells at the base 

 of the petiole. 



(3) The same or practically the same as both parents: 

 In the size and appearance of roots ; length of the pedi- 

 cels ; size of the sepals ; size of petals ; width of the epi- 

 dermal cells on the transverse section of the root; 



