KNOWLEDGE OF MONOCOTYLEDONOUS SAPROPHYTES. 195 
the whole of the epidermis is hairless. From this it may 
be concluded that the hairs were evolved (or preserved ?) to act 
as absorbing organs. 
General Remarks on Epipogum nutans. 
The fact that the rhizome-axis is all but perfectly covered by 
scales, which adhere closely and tenaciously to it, at once suggests 
that the latter are the absorbing organs of the plant. This view 
is confirmed when we note that countless long hairs grow out 
from the exposed epidermis of the scales, also that these hairs 
penetrate masses of humus which are permeated by fungal hyphe, 
and that mycorhizal hy phe enter the hairs and occupy all the cells 
of the scales. That the hairs perform their particular functions 
when the scales are underground, and exposed to the humus, 
is shown by the gradual manner in which they undergo complete 
atrophy in scales placed higher up the axis. 
The shape of the cells forming the subterranean scales suggests 
that the substances absorbed by the hairs are transported to the 
bases of the leaves and thence into the rhizome, and not across 
the scales straight into the epidermis of the axis. Further 
evidence for this view is derived from the fact that the leaf-trace 
bundles may have, even at the bases of the scales, a strong sheath 
of cells containing starch, whereas no starch occurs in any other 
parenchyma-cells of the outer cortical layers. On the other 
hand, we can conclude that the inner epidermis of the scales and 
the epidermis of the rhizome prevent or retard the inward passage 
of liquids. Thus these two layers play the part of suberized 
exodermal cells; and the heavily-pitted cells at the bases of the 
scales may be compared to the passage-cells of an exodermis. 
Again, as there appear to be no mycorhizal hyphæ in the axis 
of the rhizome while there are mycelia in the scales, the latter 
may physiologically represent the exocortex of the roots of 
saprophytic orchids (Galeola, Aphyllorchis, Lecanorchis, Neottia), 
or of the axis of the rhizome (Epipogum aphyllum and Corallorhiza 
innata). 
As the rhizome is drained of its contents by the growing 
inflorescence-axis, the starch diminishes. It disappears from the 
general sheath before it deserts the bundles lying within. The 
parenchyma-cells at the base of each scale acquire slightly thicker 
walls, which become suberized, and the scales die. The advantage 
of the suberization of these basal cells when the leaves die is 
