112 
within which the growth of the apex takes place. In the central part 
of every haustorium, just below the solid mass of descending vessels, 
tliere is a layer of considerable thickness which, except at its centre, 
is formed of regular rows of oblong cells that are flattened contrary 
to the vertical axis ot the haustorium. The centre of this layer con- 
sists of rounded, irregularly arranged cells (Figs. 5 and 7). All the 
cells of this central portion contain a turbid, granular protoplasma, so 
that after staining with carmine they become quite conspicuous. 
The contact of the tissues of the parasite with those of the foster- 
root is similar to that which we observed in Cofuandra. I satisfied 
myself that there is a perfectly open communication between them. 
The meristematic, active cells enter the vessels of the foster-root 
bodily after the walls of the latter have been partly absorbed, Figs, 
10 and ir. Some vessels are formed in the haustorium, at the side 
of a vessel of the foster-root3 and then the side-wall of the latter and 
the end walls of the former are absorbed, Fig. 13; or they meet end 
to end, and then they simply form one passage after the absorption 
of the end-walls, Fig. g. 
But more interesting and more important thaux all these facts I 
consider tlie following? observation that I wish to record on this occa- 
sion. 
ft. 
ifoli 
corinected with those of the foster-root in such a way, that communi- 
cation was open between the parasite and the stem of the foster-plant, 
while communication between parasite and peripheral ends of the 
{ostcT^roof was entirely cut off. In Fig. 5 the right-hand side of the 
foster-root, at re/, if not cut off, would lead to the main root, and that 
to the stem. We observe that the tissues at the left, toward the root 
end were absorbed and replaced by the apex of the haustorium and 
that none of the entering vascular fibres turns that way. In Fig. 7 
the /e/t hand side points towards the stem. The process begun m 
these two cases has been completed in the one illustrated by Fig. 8. 
The apex of the haustorium gradually worked its way deeper and 
deeper into the hazel-root, while its tissues kept turning steadily m 
one direction: toward the stem, away from the root-end, until finally 
the latter was cut off completely and the haustorium took its place. 
The progress of this process may be seen in its various stages by ex- 
amining some typical forms of the (?<?mr^//a haustorium, as illustrated 
by Figs. I, 3, 2 and 4. 
A 
the tendency of the apex to turn away from the root-ends m a 
remarkably clear manner. That portion of the apex which would 
correspond to the portion lying to the right of the point x, in ^^S- 7' 
or to the left of x in Fig. 5 (/. e. toward the root-end), is separaieit 
from the tissues of the foster-plant, for the outermost cells of tms 
part of the haustorium have their outer walls lignified, as shown uy 
the indol and other reactions. At the same time, the adjacentcei 
of the foster-root are found to be in a state of partial decomposition, 
while on the opposite side the connection between parasite and no 
is perfect, as shown by Figs. 10 and 11 which were drawn from o 
of these slides. 
