448 Messrs Gardiner and Hill, The Histology 
the shorter end walls one large group of threads occurs, which 
occupies the whole of the wall 1 (Fig. 3). Thus, though the walls 
are unpitted, the connecting threads are arranged in groups. If 
sections of a young germinating seed are examined the cotyledon 
is seen to have increased in size, and abundant evidence of enzyme 
action is afforded by the partially broken-down walls of the 
surrounding endosperm cells. 
A careful examination of the walls of the cells in the imme- 
diate vicinity of the cotyledon, which walls moreover are crowded 
with threads, shews that the ferment effects an entrance by only 
a few of the threads, and, proceeding from the interior of the cell 
outwards, works along them towards the middle lamella, where it 
quickly becomes more active and rapidly dissolves the reserve 
cellulose in the neighbourhood of the lamella, thereby forming 
large cavities broadly fusiform in shape, which shew their broadest 
diameter at the lamella, and taper away to the edge of the wall on 
either side 2 (Fig. 8 (; y )). 
In this region, owing no doubt to the mucilaginous character 
of the lamella and adjoining layers of the wall, the enzyme is more 
vigorous and effective than on the younger and more horny layers 
of the cell membrane. As the ferment action proceeds these 
cavities break into one another, and so the whole wall becomes 
disorganized and in its altered and mucilaginous condition now 
stains with the dyes employed for demonstrating the ‘ connecting 
threads.’ The tracks of the threads can, however, still be seen 
after the cell walls have become disorganised (Fig. 8). 
If sections of a seed are examined, which has been allowed to 
germinate for a longer period and in which the cotyledon has 
enlarged so considerably inside the seed as to have displaced the 
greater part of the endosperm, it is found that the ferment attacks 
the cell walls of the more peripheral portions of the endosperm in 
a somewhat different manner to that just described, for whereas 
we have shewn that the ferment dissolves the walls of the rounded 
cells at the centre of the seed, more particularly in the region of 
the lamella, in the older walls it commences its attack at the inner 
or free edge of the wall, and proceeds outwards, in a V-shaped 
manner towards the middle lamella (Fig. 9). These differences in 
the method of the ferment action on the cell walls appear to be 
due to some differences in the composition of the ‘reserve-cellulose’ 
in different parts of the endosperm. 
The amount of endosperm tissue undergoing dissolution at any 
given time is comparatively small, since the action of the ferment 
is localized to the layers of cells immediately surrounding the 
1 Cf. Gardiner, Proc. Roy. Soc., 1897, Fig. 1. 
2 Cf. Hill, Ann. Bot., vol. xv. 1901, fig. 13, PI. XXXII. p. 596. Also Gardiner, 
loc. cit. fig. 3. 
