Ill 
it is still more difficult to prepare perfect longitudinal sections. How- 
ever, I never failed to see this epidermis, as I must call it, on thin, 
/. e, young portions of the Gerardia root, while on older ones I could, 
at best, make out a few shreds only. I must therefore suppose that 
the epidermis is soon cast off. I am not prepared to assert that 
these epidermal cells perform the functions pertaining to root-hairs, 
but, considering the thinness of their membranes, which do not seem 
to be cuticularized, and their peculiar inflated form, I do not see what 
should prevent them from absorbing the water from the soil in case 
the plant needed it. 
Referring to this description of the root, the. structure of the 
haustorium itself will be more easily understood. With Gerardia^ 
the body of the root from which the haustorium grows, contributes 
a much greater share to the bulk of the haustorium than with Coman- 
dra. We can see from Figs. 5 and 7 that a considerable portion of 
the upper half of the haustorium really belongs to the root proper. 
■^^ Fig. 5, representing a longitudinal section of a hazel-root that 
bears a haustorium In the manner illustrated by Fig. 3, the vascular 
cells of the Gerardia root,//, appear cut across, for it had grown at 
right angles with the foster-root. In Fig. 7 the vessels of the Gerar- 
dia root, pl^ are viewed longitudinally, Gerardia and hazel-roots 
lying in the same plane. 
The epidermoidal layer of the haustorium is continuous with that 
of its root (Figs 5 and 7, ep), and the epidermis, e, is also met with 
on the haustorium. It is found especially well preserved in the 
angles at which the haustorium and the foster-root meet (Figs. 5 and 
7i 0. In and near these places the epidermis-cells have so multiplied 
as to form several irregular layers; no doubt, they help the Gerardia 
to get a better hold of its host. 
The portion of the haustorium-bark underneath the epidermis, 
ik, is likewise a continuation of the root-bark. The parenchyma 
cells near the epidermis are larger than those nearer t*lie centre; the 
former contain much larger starch-grains. The endodermis of the 
root is also continued in the upper part of the haustorium ; in Fig. 
6, it is indicated by a dotted line, en. The sclerenchyma-cells are 
ofthe same structure and similarly arranged in both root and haust- 
orium ; they are, as a rule, more numerous in old haustoria. The 
cortical portion does not penetrate into the foster-root, but ends at 
its surface. 
From the central wood-cylinder of the root very numerous vessels, 
surrounded by a zone of cambium, spread downward like an umbrella, 
but in a solid mass, Figs. 5 and 7, vs. Before they reach the middle 
of the haustorium most of them end abruptly, anastomosmg, how- 
ever, by means of short connecting vessels. Many of these vessels 
continue their course, singly, through the lower part of the haustorium 
to its apex, until they reach the wood tissue of the foster-root (tigs. 
5, 6, 7 and 8). They consist of comparatively short links, the ends 
<^f which are laterally connected, and are transformed into continu- 
ous passages in the usual manner, by the absorption of their septa. 
, These vascular fibres are accompanied, in their lower course with 
elongated, active cells, ac, which constitute the menstematic tissue 
