LEAVITT: TRICHOMES OF ROOT. 
293 
length to breadth was found in cases to be 27 :1 — and, between 
their ends, the peculiar trichomes. The bases of the latter, 
with abundant granular protoplasm, push out under the cells 
standing next above and below, and press their inner walls into 
the adjacent cortical tissue. Early stages of the trichomes are 
shown in figure 37 to 40 (plate 17). The trichoblasts origi¬ 
nate as short, proximal segments. In longisection they at first 
appear tabular, later conical, with expanded inner base. In 
tangential section they appear lenticular, and narrower than the 
atrichomic cells. JVaias flexilis (pi. 17, figs. 41, 42) agrees with 
JV. gracillima. JVaias major , JV. minor. The descriptions by 
Sauvageau show that the trichomes are of the same character 
as those of JV. flexilis. The hairless^ cells ultimately fall away, 
leaving the hairs still standing in a living condition as shown 
by the contents. 
Alisrnaceae: Limnocharis emarginata , L. Humboldti , Alisma 
Plant ago, A. ranuncidoides (Juel, l. c.), Sagittaria Eatoni , 
S. lancifolia (pi. 17, fig. 47), S. montevidensis, 8. natans , A. 
subulata (pi. 17, figs. 45, 46), A. variabilis , Lopliotocarpus 
subulatus. 
Hydrocharitaceae: Limnobium Spongia. The root-hairs are ex¬ 
traordinarily large and long, from cells, exceeding the neighbor¬ 
ing cells in breadth and depth, in amount of protoplasm, and in 
the size of the nucleus (pi. 17, fig. 51). The appearance of the 
trichoblast near the edge of the root-cap, is shown by figure 
49 (plate 17). Stratiotes aloides closely resembles the above 
species in respect to trichomes of the root. A description has 
been given by Kny. Ilydrocharis JMorsns-ranae and Hydro- 
mystria stolonifera, are included in his account. “In the three 
species named root-hairs arise from only a small number of epi¬ 
dermal cells. Those cells which are destined to grow out 
[into hairs] lie scattered amongst the others without recogniz¬ 
able order.” ] Kny says that the hair fundaments are first pro¬ 
duced where the root begins to penetrate the mud in the places 
where these plants grow. Vallisneria spiralis and Elodea 
canadensis show trichoblastic hair-cells. 
1 Kny, L. : Sitzungsb. d. hot. vereins d. prov. Brandenburg, 20 April, 1878, 
p. 48. 
