On Gymnospermous Seeds. 153 
shows a number of irregular, alternating summits and depressions. 
Whilst the integumental region in this way invades the prothallial 
area, this latter undergoes radial extension between the ridges. 
The area of contact of the two active tissues is thus continually 
increased and it is difficult to avoid the conclusion that rumination 
plays an important part in the nutrition of the endosperm. In this 
connection the distribution of chlorophyll in the transverse section 
of the seed is instructive. This is shown by the shading in text 
figure 6. The aril is coloured green throughout, the pigment being 
deepest at the periphery. The containing epidermis is richly pro¬ 
vided with stomata and all the conditions necessary for an effective 
assimilating apparatus would seem to be present. The outer zone 
of the integument (sc) which will form the stone or sclerotesta is 
colourless, but its inner layer (i) is provided with chlorophyll. The 
narrow nucellar zone (n) and the prothallium are also colourless, 
but of course the intrusive radial plates bring chlorophyll-tissue 
Text figure 6. 
Transverse section of ripening seed of Torrcya nucifera cut 
midway between attachment and micropyle. Aril, integument 
and nucellus are all confluent in this region. The general shade 
on the outer and inner zones represents the distribution of chloro- • 
pliyll, deepest (dark shading) at the surface of the aril, a, aril 
with numerous gum canals; v , in black, the vascular bundles, here 
running near the inner limit of the aril; sc. colourless outer zone 
of integument in which the hard shell or sclerotesta will subse¬ 
quently differentiate; i, inner portion of integument (soft emlo- 
testa) from which arise the intrusive ridges; n, the colourless 
inner border represents the nucellus in this region; mw, wall of 
macrospore ; ps, prothallus ( x 4^). 
