OP CEYLON AND INDIA. 
297 
making the inner tissues more retentive of their water, just 
as is supposed to be the case in some of the Crassulaceæ, 
e.g.^ Rochea falcata. The silica is by no means universally 
present, nor in all parts of the plant ; it is confined mainly 
to the thalli, which are the parts most able to produce new 
growing points and resume their growth after a period of 
exposure. 
Passing on now to deal with the secondary shoots, which 
in this species make up the bulk of the plant, do most of the 
work of assimilation, and ultimately bear the flowers, we 
shall consider first the most fully developed type of shoot, 
and afterwards the reduced shoots mentioned above as some- 
times found on the thalli. 
The growing point emerges endogenously from the 
thallus, as already mentioned. It is of an ordinary shoot type, 
bearing leaves closely packed together. The phyllotaxy 
is complicated, and I have not been able to make it out 
satisfactorily. The leaves are of simple structure, very 
delicate, not unlike the leaves of a moss ; they resemble those 
to be described below for the ramuli, but are larger, and have 
often a central portion more than one cell thick, like the 
leaves of Lawia described below. 
The most noticeable feature about the growing point is 
the very early formation of shoots of the second order, 
which grow very rapidly and cover up the main apex with 
their leaves, thus rendering it difficult to dissect out the 
principal growing point. These shoots are shoots of limited 
growth, or, as we have called them above, ramuli ; they do 
not repeat the structure of the main stem. The growing 
point of a ramulus is figured in PI. VII., fig. 11. It has 
a well-marked dermatogen layer, with inner meristematic 
layers, and gives rise to a large number of leaves lower down, 
these leaves being only one cell thick, four cells broad (in 
the S. Kanara material), and exceedingly delicate. The tip 
of one of these leaves is shown in PI. VII., fig. 13, and 
the basal part in optical section in fig. 14. The basal cells 
