the Seed in the A Isinoideae. 
5i 
the drying up of the cells composing it, we get a mechanism in which the 
latter function is often at a discount. In Spergularia satinet ■ winged 
and un winged seeds occur in the same ovary (PL VI, Figs. 31, 34). In 
other species the same condition obtains, but more exceptionally. This 
•fact suggests that water storage is the determining factor in the proliferation 
of this tissue, and where the supply of H 2 0 is deficient, or unequally 
distributed, the process of formation is interrupted. Therefore we might 
consider the local hypertrophy which is the origin of this band of tissue to 
be entirely suppressed in the Alsineae, and look upon the specialized layer 
of very active cells, capable by division of keeping pace with the growing 
ovule, and possibly of regulating water storage, as an advance in organization. 
Finally, then, everything seems to point to the conclusion that the 
Alsinoideae are members of a very old and stable family. On one side 
they suggest an intermediate stage in the development of the ex- albuminous 
seed by a progressive reduction in the functions of the nucellus. The cor- 
relative increase in the activity of the endosperm results in the reserve food 
material being stored in the embryo itself through the medium of the latter 
tissue; M. Pechoutre’s researches on the Rosaceae seem to point to that 
family as providing further illustration of the same tendency. 
Among the points of comparison afforded by the Rosaceae may be 
mentioned the functional role played by the endosperm where some 
portion persists in the ripe seed. 
The endosperm in this family is characterized by a limiting peripheral 
proteid layer (assize proteique), distinguished by abundant proteid reserves, 
but not otherwise differentiated from the other layers. In all cases some 
of this tissue persists in an active Condition in the ripe seed. The conclusion 
drawn by Pechoutre that the function of this tissue is not mechanical, as in 
the case of the seed coat to which it is fused, but rather physiological in 
character, seems to be justified. 
In the Alsinoidean stage of development the endosperm is limited to 
one layer only, and its function is entirely secretory and digestive. When 
this tissue increases in volume, the outer layer is specialized as a ferment 
layer, the increase in volume being associated with the increase in activity 
necessary to the transference of all the reserve food material through the 
endosperm to the embryo before germination, instead of its being stored in 
the nucellus to be drawn upon as required. If we consider the other end 
of the scale and take certain Piperaceae as a starting-point, a great 
restriction in the function of the endosperm is apparent in the Alsinoideae. 
In the Piperaceae the embryo at maturity is an undifferentiated mass of 
cells, and on germination the endosperm extrudes from the seed coat and 
jackets the embryo till cotyledons, hypocotyl, and root are organized. 
In the Alsinoideae the endosperm has no other function beside that of 
secretion and digestion, and it does not bring these powers into play until 
