26 Gibbs. — Notes ok the Development and Structure of 
seed-coat and continuing to jacket the embryo, which at germination is 
only an undifferentiated mass of cells, until the root, hypocotyl, and cotyle- 
dons are organized. This endosperm is not a storage tissue, but digests 
the perisperm reserves and passes them on to the embryo. The suggestion 
is therefore made that this restriction of the function of the endosperm 
obtains in all seeds with abundant perisperm, the sporophyte of the second 
generation being nourished, not by the parent generation, but by the 
intervening gametophyte. 
A chance series of sections through a mature seed of Stellaria 
aquatica which seemed to prove the justice of this point of view, led 
to the present investigation which rather confirms Johnsons hypothesis. 
To understand the organization of the mature seed, it was necessary to 
trace the separate tissues composing it to their origin, and the subsequent 
results seemed sufficiently interesting to justify publication. 
Great uniformity and simplicity of structure prevails in all members of 
the Alsinoideae examined. 
This fact renders the progressive and comparative development of the 
nucellar tissues, in conjunction with that of the embryo-sac and embryo, easy 
to follow. Some stress has been laid on this point, as the part played 
by the separate tissues of the ovule in the development of the embryo are 
especially accentuated in this case, owing to the early laying down and 
abundance of the perisperm coupled with the restriction of the functions of 
the suspensor and endosperm. 
Morphologically these ovules are characterized by the constant presence 
of two integuments, each composed of two layers of cells, the inner integu- 
ment always projecting beyond the outer one. The nucellus increases 
in size by the periclinal and anticlinal divisions of the epidermal layer, and 
this results in the sinking of the embryo-sac in the nucellar tissue, and the 
formation of a sort of transitory beak at the apex of the nucellus by the 
outgrowth, prior to fertilization, of certain cells which are subsequently 
reabsorbed. 
The chief feature in the embryology is the filamentous suspensor, the 
basal cell of which (that directed towards the micropyle) attains to a very 
large size. 
The uniformity that characterizes the endosperm in these ovules is 
very striking, and one of the chief objects of this research is to determine 
the function of the cells of this tissue in relation both to their morphological 
differentiation, and to the nutrition of the embryo. 
Variation being so slight in the tribe Alsinoideae, one species is taken 
as a type. 
Stellaria media , L., was chosen as offering a good example, and it was 
studied as far as the maturation of the seed, partly because the basal 
suspensor cell reaches its maximum development in this species. 
