44 Gibbs. — Notes on the Development and Structure of 
starch, but the water stomata were not apparent till the formation of the 
root hairs, therefore not until the emergence of the hypocotyl, when root 
pressure would first be felt and some organization to regulate osmotic 
pressure must be called into play. The cotyledons are therefore perfect 
foliage leaves, the organization of which is complete long before they 
emerge from the seed coat. 
The root apex of the embryo shows well-marked stratification in the 
mature seed with the root cap differentiated. Starch appears in the 
columella of the root cap after the differentiation of the root hairs (Fig. 34, 
sth.). This starch is localized to a few central cells of the columella and is 
evidently statolithic in function, as the grains are relatively few in number 
and only occur towards the base of the cells in normally growing seedlings. 
Specific Differences. 
Sperguleae. Spergidaria rubra and Spergula arvensis. 
Specific difference is rather marked in the Sperguleae, and runs in one 
or two lines more suggestive of a primitive form than variation from type. 
In both Spergula arvensis and Spergidaria rubra the nucellus is very 
much curved, bringing the micropyle almost in contact with the funicle, 
simulating an anatropous ovule. This peculiarity may be due to the 
greater packing of the ovules in the ovary, in Spergidaria rubra especially 
they are extremely numerous. 
The layer 2 of the inner integument shows an especial modification in 
Spergula arvensis. In the region of the endosperm cap and continued 
above it for a certain distance this layer consists of small and active-looking 
quadrate cells (Fig. 23, i. i. 2) which become strongly cuticularized, preserving 
their well-marked outline both in the mature and germinating seed (PI. VI, 
Fig. 30, i. i. 2). 
Layer 1 of the inner integument is indistinguishable. Over the rest of 
the ovule the inner integument behaves in the usual manner, viz. both 
layers fusing owing to the breaking down of the connecting walls through 
the extreme stretching they undergo to keep pace with the growing ovule 
(Figs. 23 and 29, i . i.). In Spergula arvensis layer 2 of the outer integu- 
ment also undergoes modification, a local hypertrophy of tissue caused by 
the proliferation of the cells of this layer forming a wing all round the 
ovule in the vertical plane of the embryo (Fig. 23, w.). This wing is 
composed of small polygonal cells elongated in longitudinal section with 
very small nuclei and thin contents. As the ovule matures this tissue 
dries up, the empty cells remaining as an investing wing ; it therefore serves 
a secondary function as a mechanism for wind dispersal. A water jacket 
may possibly be the first function of this proliferation of tissue. The 
appearance of the cells suggests water storage in the absence of dense 
staining contents which would characterize proteid preserves. They also 
