Groom . — On Dischidici rafflesiana ( Wall.)* 237 
so fundamental as to prevent the two being described to-^ 
gether. 
In the young stage the root is clothed externally by a layer 
of epidermal cells, many of which grow out into root-hairs. 
In the attaching-roots these hairs are mainly developed on 
the side of the root which is in contact with the surface of the 
host-plant ( £ ventral side ’) : elsewhere the root-hairs are much 
less numerous and are smaller. On the ventral side they 
form a dense mycelium-like weft, the marginal root-hairs of 
which are longer, whilst the central ones are very short 
(Figs. 2, 9). Each root-hair, on reaching the bark of the 
host, bends and runs for some distance over its surface. In 
the younger parts of some attaching-roots there is a curious 
grouped arrangement of the ventral hairs ; when the root is 
examined from above, one sees that in each cluster of hairs 
there is a gradual increase in the length of the marginal hairs 
as we travel away from the apex, and then there is a diminution 
in their length : then follows a space with a few dwarfed hairs 
which are in turn succeeded by another cluster similar to that 
described. Whether this curious grouping be due to 
differences in the degree of contact, or to irregularities in the 
mode of distribution of moisture or nutritive matters on the 
surface of the bark, I cannot say. It seems probable that the 
formation of numerous and large root-hairs is not solely a 
phenomenon due to contact. For, in the first place, on 
pitcher-roots the hairs are longer and larger on the side 
towards the solid contents. In the second place, in one case 
it was observed that an attaching-root spread over some 
Mosses clothing the trunk of the supporting tree : and though 
the root was separated from the moss-leaves by an appre- 
ciable distance, yet, on the side facing them, it developed 
numerous large hairs which spanned the intervening space 
and finally spread over the surface of these leaves. In the 
third place, long hairs are occasionally developed on the sides, 
and even the dorsal face, of an attaching-root : and, in this 
case, they are directed parallel to the supporting surface, or 
are even obliquely inclined towards it. The latter two facts 
