6io 
Notes . 
solution their yellow tinge deepens, and after treatment with iodine and sulphuric acid 
they become brown; this coloration in each case passing in the outermost layers 
into the ordinary bluish tinge of a cellulose reaction. From these facts, it seems 
probable that they are composed of a hardened horny variety of cellulose, like the 
‘ reserve cellulose ’ described by Gardiner and Hill 1 in the endosperm of Tamils, and 
by Griiss 2 in that of Phoenix and other plants, which is also unaffected by ordinary 
cellulose tests, and reacts similarly with iodine in potassium iodide and with iodine 
and sulphuric acid. As in Tamus , moreover, the middle lamella is not evident in 
most of the walls when mature, though in the outermost layers, and fairly often among 
the other large cells in the ridges, it can still be recognized as a fine line. Otherwise, 
the layers of the walls of adjoining cells seem to coalesce to form a homogeneous 
intercellular matrix. 
A similar transformation takes place in the outer wall of the inner epidermis (c), 
which also becomes thickened and loses its cellulose reactions. Otherwise, this 
epidermal layer remains unaltered, except that the cells increase in size and a crystal 
of calcium oxalate appears in each. 
Meanwhile, the outer epidermis (d) is developing into the sarcotesta, which 
is formed entirely from this layer. Over the ridges it remains single, the cells merely 
increasing in size, but between the ridges the cells elongate perpendicularly, and 
divide several times by transverse walls. By continued elongation as the ridges 
of the endotesta rise up, they fill up the hollows between them, so that the surface of 
the seed remains smooth. In the latest stages they become separated from the endo¬ 
testa towards the bottom of the hollows (Fig. 4). As the epidermis develops, its outer 
wall becomes much thickened and striated. 
As the water in the seed-coat evaporates, the sarcotesta shrivels up, and sinks 
into the hollows between the ridges of the endotesta, whose thick-walled cells retain 
their shape. When moistened, both layers rapidly absorb water. The cells of the 
sarcotesta expand to fill up the hollows once more, and the outer epidermal wall 
swells up considerably, so that the surface of the seed becomes smooth and shiny. 
The cell-walls of the endotesta also expand slightly, and water replaces the air in their 
lumina, so that the whole seed-coat becomes a spongy reservoir for the developing 
embryo to draw upon. 
E. L. STEPHENS. 
Botany School, 
Cambridge. 
1 Gardiner, W., and Hill, A. W.: The Histology of the Endosperm during Germination in 
Tamus communis and Galium tricorne (Proc. Camb. Phil. Soc., xi, 445-57, PI. V, 1902). 
2 Griiss, J.: Studien iiber Reserve-Cellulose (Bot. Centralbl., lxx, 242-61, 1897). 
