244 ORR—THE OVULAR INTEGUMENTS AND TESTA 
Cleome spinosa, Jacq. 
The ovules of Cleome possess two integuments which originate 
from the base of the ovule in the usual way. At maturity, 
the outer integument consists of two layers of cells, while the 
inner integument is composed of one outer layer of comparatively 
large thin-walled cells with sparse protoplasmic contents, and 
three layers of small cells on its inner side. The outer layer, 
with its large clear cells, has the appearance of aqueous tissue, 
Fic. 1.—Micropylar region of the ovule of Cleome spinosa, showing at A the 
initiation of the lignified tissue. x 350 
and no doubt does function at this stage as a distributer 
of water. 
An examination of longitudinal sections of the young ovule 
revealed, further, the presence of conspicuous patches of re- 
latively large thick-walled elements, characterised by spiral and 
reticulate thickening of the cell walls. These lignified elements 
were confined entirely to the tissue of the inner integument in 
the region of the micropyle (fig. 1). In the older ovules, these 
thick-walled cells extend from the outer margin of the in- 
tegument inwards to the micropyle, abutting directly on the 
slit, and giving to the ovule a somewhat unusual appearance 
(fig. 2). Sections cut transversely through this region, at this 
stage, show that these lignified cells are disposed in the form of 
a broad ring completely encircling the micropylar pore. These 
