OF CEYLON AND INDIA. 
295 
describe them here in a little detail, and reference may be also 
made to Warming’s descriptions and figures. A hapteron 
may appear at any part of stem or root which is near the 
rock ; it appears as an exogenous cap-less outgrowth, grow- 
ing by a meristem at the apex, and bending downwards 
under the influence of gravity to reach the substratum, on 
which it flattens itself out, often developes root-hairs, and 
becomes very firmly attached by a kind of dark-coloured 
cement which is secreted by the root-hairs, or perhaps some- 
times by the surface cells. It very often branches exo- 
genously, or is merely lobed. All cases may be seen in the 
various figures given below and by Warming. 
A hapteron may be looked upon physiologically as a 
gigantic rhizoid, and acts in the same way as an ordinary 
unicellular rhizoid, bending down to the substratum and 
adhering toit, often becoming lobed or branched. The size 
and form of the haptera in the species now under consider- 
ation seem to depend largely upon whether the thallus is 
touching the rock or not at the point where they form, and 
also upon the strain caused by the water current. In the 
Anamalai material, where the thallus touches the rock, the 
hapteron grows into a more or less discoid foot ; in the 
S. Kanara material, which grew in less rapid water, the disc, 
as the figures show, is very regular and thinner, while in the 
Mundakayam material collected by Mr. Bourdillon upon the 
edges of waterfalls, where the strain is greater, the haptera 
are larger, more lobed, and stretch further out upon the 
rocks (PI. YII., fig. 10). The formation of a discoid hapteron 
seems to be dependent on the thallus touching the rock ; 
when, as frequently in the material from S. Kanara and 
Mundakayam, the thallus is above the rock, a long tapering 
peg-like hapteron is formed, which grows down to the rock 
and spreads out upon it, while the secondary shoot appears 
endogenously at the upper and outer side of the peg (PI. VII., 
fig. 9). 
The formation of secondary shoots appears to be practi- 
cally always accompanied by the simultaneous or previous 
