204 MR. P. GROOM—CONTRIBUTIONS TO THE 
well developed before the foliage-leaf unfolds: thus in Cory- 
santhes, as the habit of the genus suggests, we are dealing with 
a hemisaprophyte. It illustrates the process of atrophy of green 
foliage-leaves till they become mere microscopical scales devoid 
of vascular constituents. The stem has become an absorbing 
organ, and developed entirely peculiar structures, before the 
plant has lost its chlorophyll. In particular this appears to show 
that we are not entitled to speak of degenerating effects of the 
loss of chlorophyll in holosaprophytes and holoparasites, for these 
changes commence before the loss of chlorophyll. It seems 
more correct to speak of the degrading effect of the absorption of 
organic matter, and to look upon the disappearance of the chloro- 
phyll as one of the many structural simplifications. 
As regards the tuber, the histological nature of the superficial 
layer and exodermis, the frequent absence of particles of humus 
from the hairs and the doubtful occurrence of mycorhizal hyphe 
in them—all these facts associated with the fact that the starch- 
grains in the tuber are large, not transitory small grains—suggest 
that the tuber is an organ especially adapted for the storage of 
food, particularly of carbohydrates, and that it is, at most, only 
secondarily an absorptive organ. Further, it seems probable 
that the hairs, at any rate later in life, function as anchoring- 
threads * rather than as absorbing-cells. 
From analogy with Epipogum nutans and Dictyostegia 
orobanchoides, it might be thought that the multicellular pro- 
tuberances, with their hairs, represented reduced leaves. This 
view is negatived by their irregular arrangement: by their 
occurrence on parts above the insertion of the reduced leaves, 
and even on the base of the one leaf: and finally by the contrast 
between the structure of the smallest scale—quite smooth and 
hairless—and themselves. The distribution of the protuberances 
with their hairs makes it highly probable that they are peculiar 
structures which were specially evolved to absorb nutrient material. 
SPIRANTHES AUSTRALIS, Lindl. 
Judging Spiranthes australis by its relatives, it seems probable 
that the plant is hemisaprophytic. And this hypothesis is 
* 'This passage was written before I heard from Mr. Ridley the habitat of 
this Corysanthes, but I judged from the structure of the hairs on the tuber 
that the plant grew on a hard solid substratum to which it was anchored 
by the hairs. Mr. Ridley found the plant growing on rocks. 
