814 



MACROSCOPIC AND MICROSCOPIC CHARACTERS OF PLANTS. 



The transverse sections of the leaves of the parents 

 and the hybrid were compared at the region of the first 

 main vein from the midrib. The upper epidermal cells 

 are rectangular and have a thick outer wall. They are 

 larger in M. vexillaria than in At. rcezlii. The cells in the 

 hybrid are identical in depth with those of At. rcezlii, 

 but in width they are between those of the two parents, 

 but much nearer At. rcezlii. (Table J 48.) 



Beneath the upper epidermis are three layers of 

 large open cells, containing no chlorophyll, the aqueous 

 tissue. The cells of the first layer are larger than those 

 of the others. They are smaller in M. vexillaria than in 

 At. rcezlii and smaller in the hybrid than in either parent. 

 (Table J 48.) 



The lower epidermis consists of cells that are very 

 little wider than deep and that have a very thick outer 

 wall. These are wider and less deep in M. vexillaria than 

 in At. rcezlii, and are smaller in both dimensions in the 

 hybrid than in either parent. (Table J 48.) 



Just beneath the lower epidermis is a layer of aqueous 

 tissue, the cells of which are wider but less deep in At. 

 vexillaria than in At. rcezlii. The cells in the hybrid 

 are wider than in either parent, but in depth between 

 those of the parents, although less near At. vexillaria 

 than At. rcezlii. (Table J 48.) 



Between the upper and lower areas of aqueous tissue 



are small rounded cells that contain chlorophyll and starch 



grains, and having intercellular spaces and strands of 



fibrous tissue among them. In this tissue are embedded 



the bundles. The first main bundle from the midrib of 



At. vexillaria is much shorter and narrower than that of 



At. rcezlii, while that of the hybrid is between the parents 



in depth, though much nearer to that of At. vexillaria 



but identical with that of At. vexillaria in width. (Table 



J 48.) 



Flower. 



Sections of the upper epidermis at the middle of the 

 dorsal sepal were examined. The cells are papillose in 

 At. vexillaria, flat or only very slightly papillose in At. 

 rcezlii, and papillose in the hybrid though the papillae 

 are not so long as in At . vexillaria. The cells are larger 

 in At. vexillaria than in At. rcezlii, and smaller in the 

 hybrid than in either parent. (Table J 48.) 



A pinkish-lavender sap is present in the upper epi- 

 dermal cells of At. vexillaria, but absent in At. rcezlii and 

 the hybrid. 



Hairs are very rare in M. vexillaria, but comparatively 

 numerous in At. rcezlii and the hybrid, especially in the 

 latter — in At. vexillaria 1 gland in 70 fields, in M. rcezlii 

 1 in 5, in At. bleuana 1 in iy 2 fields. Each hair is com- 

 posed of an elongated, thimble-like, very thin-walled cell 

 at the end, then a somewhat awl-shaped cell with slightly 

 thicker walls, at the base of which is a cell that appears 

 circular and thick-walled on surface view. In a few cases 

 two of these hairs appear together, arising from the same 

 cell or adjacent basal cells found in At. vexillaria over 

 an area of 65 microscopic fields. They were longer than 

 in At. rcezlii. They are more numerous in the hybrid 

 than in either parent, and are between the parents in 

 length, being a little nearer M. vexillaria than At. rcezlii. 

 (Table J 48.) 



The lower epidermal cells are flat and hexagonal in 

 shape. They are larger in At. vexillaria than in At. razlii, 

 and while between the two in the hybrid they are less 

 nearer At. vexillaria than At. rcezlii. (Table J 48.) 



Stomata are present on the lower surface, and they 

 are more numerous in M. vexillaria than in At. rcezlii. 

 The number of stomata in a microscopic field in the 

 hybrid is identical with that in M. vexillaria. (Table 

 J 48.) 



The numbers of stomata on the lower epidermis of 

 the dorsal sepal is : At. vexillaria and M. bleuana 0.4 in 

 a field, M. rcezlii 0.2 in a field. 



Sections of the upper epidermis of one of the lateral 

 petals were examined. The cells- in both parents and 

 hybrid are papillose. They are larger in At. vexillaria 

 than in M. rcezlii. In the hybrid they are in length 

 shorter than in either parent, but in width between the 

 two parents, although much nearer M. rcezlii. (Table 

 J 48.) 



The upper epidermal cells at the middle of the petal 

 of At. vexillaria contain a pale pinkish-lavender cell sap 

 which gives the same hue to the petal. Colored, sap is 

 not present in At. rcezlii or the hybrid. 



Hairs similar in appearance to those on the upper 

 surface of the dorsal sepal are present on the upper sur- 

 face of the lateral petals. They are much less numerous 

 and shorter in At. vexillaria than in At. rcezlii. In the 

 hybrid, they are as numerous as in At. rcezlii, and they 

 are longer than in either parent. (Table J 48.) These 

 are 1 in 7 fields in At. vexillaria, 1 in 2.2 fields injf . ra'zlii, 

 1 in 2.2 fields in M. bleuana. 



The lower epidermal cells of the lateral petal (at mid- 

 dle) are much larger in At. vexillaria than in M. rcezlii. 

 In the hybrid they are between those of the two parents 

 in length, but slightly nearer M. vexillaria; and in width 

 they are almost exactly mid-intermediate between those 

 of the parents. (Table J 48.) 



The stomata are very rare, but less rare in At. vexil- 

 laria than in At. rcezlii. The number in M. vexillaria is 

 1 in 13 fields, in At. rcezlii 1 in 27, in At. bleuana 1 in 16. 



Sections were examined of the upper epidermis of the 

 labellum at the base above the bright lemon-yellow area 

 in At. vexillaria, the orange-yellow area in M. rcezlii, 

 and the brownish-red area in the hybrid. The color was 

 found to be due to a large globular cluster of orange- 

 yellow chromoplasts together with a few isolated ones in 

 each epidermal cell of At. vexillaria; to bright orange 

 globular clusters of chromoplasts in At. rcezlii; and to 

 yellow globular clusters of chromoplasts and a reddish- 

 violet cell sap in the hybrid. In At. vexillaria there is 

 present at the anterior part of the yellow basal area three 

 deep-red veins, the color being due to a pink-magenta cell 

 sap and orange chromoplasts in the upper epidermal cells. 

 In M. rcezlii the orange-colored area has a few dull red- 

 dish-brownish-purple streaks which are due to the pur- 

 plish sap and the orange-brown chromoplasts in the 

 upper epidermal cells. In the hybrid the color above the 

 veins appears to be spread out over the yellow area, giv- 

 ing the entire colored portion a brownish-purplish-red 

 hue which is due to the yellow chromoplast clusters and 

 the reddish-violet sap in the upper epidermal cells. 



The upper epidermal cells are papillose, the papillae 

 being rather long in At . vexillaria, short in At. rcezlii, and 

 both long and short in the hybrid. The average length in 

 the hybrid is much nearer At. rcezlii than At. vexillaria. 

 The cells themselves (basal boundaries measured) are 

 shorter and wider (the width almost equalling the 

 length) in At. vexillaria than in At. rcezlii, in which latter 



