LEAVITT: TRICHOMES OF ROOT. 
295 
paratory to the formation of trichomic cells were observed about 12 
cells from the apex. The cells immediately below — the next 
younger — were of uniform size and appearance. The divisions 
mentioned segmented the mother cells into two unequal parts in 
each instance, having lengths as 3 to 2. The distal segment was the 
shorter; this was the trichoblast. From this point backward a reg¬ 
ular succession of cell-pairs was to be seen in which shorter and 
denser trichomic cells alternated with those of an opposite character 
(pi. 18, fig. 60). The series was followed up to the root-hairs, about 
0.6 mm. from the end of the root. The ultimate lengths of the two 
sorts of epidermal cells were as 3 or 4 to 1. In larger roots the 
hairless cells were 6 or 7 times as long as the trichomes. 
Luzula campestris. — The trichoblasts originate as short tabular 
segments, including the lower one third to two fifths of the original 
cell room. They are frequently divided after a short interval, either 
transversely or longitudinally (pi. 17, fig. 55). In the latter event 
two root-hairs are formed side by side, as in Lycopodium luciclidum 
and in Anigozanthos pidcherrima. The three species of Luzula 
which I have seen agree in the above particular. The incipient hair 
is inclined forward, as in several of the vascular Cryptogams already 
described. 
In all species of Glumiflorae in which the matter has been accu¬ 
rately determined, the trichoblast comes into existence as a distal 
segment in the differentiating division. 
I have examined the following species of the Glumiflorae and find 
the presence of predetermined hair-cells. 
Juncaceae: Juncus acuminatus. The trichoblast is from the lower 
end of the mother cell. It often divides transversely so that 
2 or even 3 trichomes may stand in succession (pi. 17, fig. 53). 
Juncus arcticus . The origin and superficial appearance of the 
trichoblasts is shown in figure 52 (plate 17). Juncus glaucus. 
The trichoblast is cut off distally. Juncus marginatus , J. mil¬ 
itarise and J. tenuis . Luzula campestris , X. comosa , L. sude- 
tica (pi. 17, fig. 54-56). 
Cyperaceae: Carex albicans , C. conoidea , C. crinita , C. foenica 
var. sabulonum, C. Houghtonii, C. maritima, C. Muldenbergii , 
C. muricata, C. pennsylcanica , C. Tuchermanii , Gyperus alter- 
nifolius (pi. 18, figs. 58, 59), C. filiformis , C. natalensis, C. 
