Notes. 
609 
greatly in size and elongate vertically, so that in the mature seed they form a pave¬ 
ment, six to ten cells broad, running along the bottom of these depressions (Figs. 4 
and 1, b). 
As these ridges develop, the cells composing them increase greatly in size, while 
those of the original integument remain small. The mature integument (excluding 
Fig. 4. Transverse section through mature seed-coat, showing further development 
of the ridges of Fig. 3. x 60. 
the epidermal layers) thus consists of a region of cells with small lumina passing at 
the ridges into cells with much larger lumina (Fig. 4). As the seed-coat matures, 
these cells all begin to lose their contents, and their walls become thicker and rather 
hard (but not lignified) and take on a yellowish colour. The response of these walls 
to the ordinary tests for cellulose, both staining and microchemical, grows fainter, 
until in the mature seed only the outermost still unaltered layers give any reaction 
with these tests. With a solution of iodine in potassium iodide and with Schulze’s 
