244 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 
is broadly elliptic, and is on the average 220x165. The head of each 
hair in D. intermedia is ovate-truncate and measures 230x105. That 
of the hybrid is elliptic-ovate in outline and measures 210 x 125 p. 
The upper laminar epidermis of D. filiformis consists of cells which 
are highly variable in size and shape. Stomata are abundant, as many 
as nine being in a circular area 300 w across. Each stoma measures 
40 x30 ,. Four-celled sessile glandular hairs are also disposed over the 
epidermis. The stomata and glandular hairs of the lower epidermis are 
about equally as abundant as those of the upper epidermis. The upper 
epidermis of D. intermedia has on the average seven stomata over the 
above-named area, and each measures 27x22. Two-celled glandular 
hairs take the place of the four-celled ones of the other parent. In the 
hybrid an average of eight stomata is observed in the above area, and 
each measures 84 x25. There isa curious admixture of the glandular 
hairs. Some are two-celled only, as in the latter parent, others are four- 
celled, as in the former, while not a few are three-celled owing to a 
median or somewhat oblique wall crossing one of the twin cells. On the 
lower epidermis the same peculiarity occurs, though in leaves examined 
the majority were two-celled, as if the glandular tissue swayed toward one 
parent. Suggestive cytological considerations come up here of which we 
shall speak later. Chloroplasts occur in all epidermal cells, but these 
vary considerably in different cells and individuals, so that exact com- 
parison seems impossible. 
(b) Axis of Inflorescence.—Comparison of a considerable number of 
axes of the parents with the eleven of the hybrid indicates that the 
average height of that in D. filiformis is 9} inches, in D. intermedia 55 
inches, and in the hybrid 6? inches. Here it should be noted that the 
average heights given for the parents have been taken from the plants 
srowing in several localities, and that the hybrids do not seem to have 
attained the age vigour which may yet be expected. This may to some 
extent affect the length of the axis. 
Surface views of the epidermis of the axis show a quite glabrous 
surface in D. filiformis with stomata in considerable numbers, each 
measuring 40-44 » in length. That of D. intermedia is provided with 
stomata which are 35— 36 « in length, but about as abundant as these are 
the two-celled glands typical of the species. In the hybrid the stomata 
average about 38 », while the two-celled glands of the latter parent are 
reproduced in size, but reduced in number. 
A slight reference may be made now to the structure of the cortex. 
In D. filiformis this is made up of 4—5 rows of thin-walled, richly 
chlorophylloid cells, with considerable intercellular spaces between. An 
indurated sclerenchyma zone next succeeds, composed of 5—6 layers of 
cells, which gradually become larger towards the interior. The amount 
of thickening is greatest in the second and third layers of sclerenchyma. 
The average thickness of the thickest walls is 7—8 ». The chlorophylloid 
cortex of D. intermedia consists of 1—2 layers of cells with fairly large 
intercellular spaces between. Subjacent to this are 83—4 layers of shghtly 
indurated, but mostly very large, cells from the second layer inwards. 
The average thickness of the walls is 3°54. The outer cortex of the 
hybrid is made up of 2—3 Jayers of chlorophylloid cells, with relatively 
