OF CEYLON AND INDIA. 
383 
this cannot satisfactorily be done, and sometimes it cannot 
be decided what is the true state of affairs. Sometimes, 
however, the endogeny can be made out by tracing the cells, 
and at the junction of the two organs a few remains of cell- 
walls or a break of continuity in size or mutual interweaving 
of the cells may be seen. The endogeny, Avhen it occurs, is 
usually only under one or two layers of cells, and as soon 
as the organ emerges, its surface cells come to the same level 
as those of the organ from which it springs, obliterating 
almost completely the proofs of endogeny. 
To return to the case in hand. The exogenous outgrowth 
is a hapteron, the endogenous the first appearance of the 
thallus. In about half of the few cases I have studied, 
there was always one endogenous outgroAvth, which could 
be recognized as thallus by the structure of its growing- 
margin. In the remaining cases, the organ which cnild be 
definitely stated to be thallus arose without doubt in an 
exogenous manner. We have therefore in this plant a 
transition case, the thallus sometimes forming exo-, some- 
times endo-genously. 
The seedling thus forms a thallus and one or more hap- 
tera at the very earliest stage. Some of the figures show 
other seedlings with more than one hapteron, but none of 
the few cases that I was able to examine showed a formation 
of more than one thallus, though I suspect that this does at 
times occur. 
The cotyledons are opposite to one another, with slightly 
channelled upper sides, and are awl-shaped. They continue 
to grow in size for a little while, as the various figures show. 
The upper side is very hairy, with long unicellular hairs. 
This is an interesting case of adaptation appearing in the 
actual embryo, for the mature leaves of this, as of many other 
species of this family, have hairy upper surfaces. Between 
the cotyledons is visible a very minute plumule. The 
figures above mentioned show several stages a little more 
advanced. The seedlings shown are all, it will be noticed, 
upon old capsules, for it was only in such positions, as a 
