194 Yapp . — Two Malayan ‘ Myrmecophilous * Ferns. 
shown in Fig. 13. I have found no mention of these by 
previous writers. 
Immediately below the epidermis is a somewhat ill-defined 
hypoderma, consisting of several layers of small and compara- 
tively thick-walled cells. Internally the latter pass by degrees 
into the larger parenchymatous cells of the ordinary cortex. 
On approaching the galleries the cells of the ground-tissue 
again diminish in size, and form a zone of small cells, several 
layers deep, surrounding the galleries. The cells of this zone 
also form numerous more or less irregular promontories pro- 
jecting for a short distance into the lumina of the galleries 
(Fig. 12). The walls of these small cells are considerably 
thinner than those of the hypoderma. In the partition-wall 
between two adjacent galleries the ordinary cells of the 
ground-tissue are usually narrow, and elongated in the direc- 
tion of length of the partition-wall. They present the appear- 
ance of having been crushed. 
At a comparatively early period, prior to the disintegration 
of the large-celled tissue, the walls of the two or three layers 
of small cells immediately surrounding it become impregnated 
with a yellowish-brown colouring matter (Figs. 9 and 12), 
which is probably the same as that found in the sclerenchyma 
of most Ferns. The same is true of the thick-walled hypo- 
derma. Later, the brown colour gradually extends to the 
whole of the ordinary ground-tissue, until the latter, when 
seen in mass, has a deep-brown or almost black appearance. 
It is this wholesale impregnation of the cell-walls with 
colouring matter that causes all except the youngest parts 
of the stem to appear black and dead. According to Walter \ 
the brown colouring matter itself is a substance called 
phlobaphene. As Poirault 2 and Boodle 3 have found in other 
Ferns, the cell-walls can be decolourized by Eau de Javelle, 
and will then give the cellulose reaction with Schultze’s 
solution. Poirault 4 also states that membranes impregnated 
with this brown colouring matter are much more resistant 
1 Walter ('’ 90 ), p. 18. 2 Poirault (’ 93 ), p. 127. 
3 Boodle (’ 01 ), p. 361. 4 Poirault, loc. cit. 
