184 MR. P. GROOM—CONTRIBUTIONS TO THE 
leaf. The plant as a whole is less xerophytic in structure than 
is Galeola; everywhere it is coated with an external layer of cells 
which have walls thinner and less cuticularized than in Galeola 
(excepting the isolated spots on the scales of the latter). Whether 
this is to be associated with the particular nature and habitats 
of the two plants, or with the fact that Aphyllorchis has a more: 
extensive absorbing surface, it is impossible to say. 
LECANORCHIS MALACCENSIS, Jtidl. 
This holosaprophytie orchid was first described by Mr. H. N. 
Ridley in the Transactions of this Society, 2nd ser., Bot. vol. Hi. 
p- 377, and he was good enough to send me one of his specimens. 
Plate 65 in Mr. Ridley's paper represents the specimen, and 
shows a descending rhizome to which are attached a number of 
feebly branching, horizontally extended roots. Two inflorescence- 
axes rise from one end of the rhizome. 
Histology of the Root. 
The adventitious roots of this plant are long, feebly branched, 
slightly succulent, and extend horizontally from the vertically 
descending rhizome. 
Externally the whole root-system—the young. parts as well as 
the old—is coated with a dense covering of particles of humus. 
This suggests that the older portions of the roots are able to 
absorb, just as are the younger, and histological investigation 
confirms this view. 
To describe first the structure of a mature part of the root :— 
(1) The piliferous layer is represented by a single layer of 
cells. None of these cells grow out into root-hairs. In most 
regions of the roots this layer persists, though here and there- 
are patches where the cells have been partially disintegrated, so 
that only their lateral and inner walls persist. The cells are 
elongated in the direction of the root-axis; their walls are thin, 
but lignified, and a delicate cuticle clothes them externally. 
The walls are not evenly thickened ; delicate filamentous thick- 
enings mark the longitudinal walls in a direction at right angles 
to their length (Pl. V. fig. 5). Most of the cells are devoid of 
protoplasm, but isolated cells outside the passage-cells of the 
exodermis are shorter, with more evenly thickened walls, and 
retain their protoplasm and a clearly defined nucleus. Thus the 
piliferous layer is represented by a slightly modified velamen con- 
