172 
Notes. 
This ridge of parenchyma runs forward for some distance, finally 
ending in a small obliquely truncate conical projection inclined some- 
what towards the apex. The endodermis forms a complete sheath 
around the projection except at its apex. The parenchymatous 
strand therefore communicates with both pith and cortex at the leaf- 
gap, and with the latter again at its forward termination. 
The xylem ring, having closed up again after the leaf-gap, becomes 
especially thick opposite the projection, so that it forms a small out- 
ward protrusion underneath it. Immediately in front of this point 
the phloem ring becomes complete once more. The endodermis 
sheathing the projection usually bulges out in a saccate manner on 
the side nearest the apex, so that the open surface of the cone faces 
obliquely backwards. It is immediately above this aperture that the 
internal termination of the canal is situated. The canal runs from 
the surface of the stem obliquely backwards towards the tip of the 
projection, but just before its blind end it usually bends slightly 
forwards towards the apex. 
In transverse sections of the stem the canal appears as a very 
narrow slit at different depths in the cortex according to the level of 
the section ; the cortical cells in contact with it are arranged more or 
less radially around it. The termination of the canal occurs at the 
point where the trace of the leaf next above is about to depart from 
the opposite side of the stele. 
These structures are of constant occurrence in all plants I have 
examined, and they acquire additional interest when it is stated that 
they are also present in the young plantlet. Some preparations made 
by Dr. Lang from young plants attached to prothalli, which he was 
kind enough to let me examine, show this to be the case, and that 
a canal is found in relation to the earliest leaves, even to the very 
first, which (allowance being made for the fact that the young plant at 
this stage is in the protostelic condition) is essentially similar to that 
described above. 
Although suggestions are possible it is not easy to find an entirely 
satisfactory explanation for these curious structures. In the first 
place it is possible that they represent the last indications of vestigial 
axillary buds. Although at the present day Helminthostachys does 
not normally branch at all, Farmer 1 finds that branches frequently 
1 Farmer, On the structure and affinities of Helminthostachys Zeylanica . Annals 
of Botany, Vol. xiii. No, LI, 1899. 
