50 Gibbs. — Notes on the Development and ''-.Structure of 
concerned, thus bear out Johnson’s suggestion that the restriction in the 
formation of the endosperm to that of a purely digestive tissue which he 
observed in certain Piperaceae, obtains in all seeds with abundant peri- 
sperm, such as Chenopodiaceae, Polygonaceae, and Caryophyllaceae, but 
he goes on to say — 
‘ Observations thus far lead me to believe that in the perisperm- 
containing seeds mentioned the embryo-sporophyte of the second genera- 
tion is never nourished by the parent sporophyte directly, but always 
through the intermediate gametophyte.’ 
This view, as far as the Alsinoideae are concerned at least, only holds 
with regard to the ultimate organization of the embryo and the germination 
of the seed. 
Before the cotyledons are differentiated everything points to the food 
material being digested and passed through the suspensor, and the embryo 
is accordingly nourished by the parent sporophyte up to that stage. It is 
only after the organization of the endosperm cap nuclei into a definite 
layer of cells that a portion of the endosperm takes on the function of 
secretory agent, which it retains till germination, when it is ruptured by 
the radicle on the elongation of the hypocotyl. A more limited function 
than is described by Johnson for the endosperm in some of the Piperaceae 
thus results from increased complexity and economy in organization ; and 
the jacketing by the endosperm of the undifferentiated embryo at germina- 
tion, which is such a striking feature in the Piperaceae, is reduced in the 
Caryophyllaceae to the short period necessary for the transference of the 
starch reserves in the perisperm to the tissues of the embryo on germina- 
tion. The endosperm cells in this order fuse up more or less completely 
with the nucellus, and remain attached to the tissue of the latter when they 
lose connexion with the embryo, which is completely organized in the 
mature seed. There is certainly an . elongation, of the cotyledons in the 
seed prior to that of the hypocotyl, but the cotyledons in this stage are 
complete leaves, with a vascular system, cuticularized epidermis, stomata, 
and air spaces, and they are also provided with an epithem tissue and water 
stomata at their apices. 
3. Trend of Development . In the Alsineae there seems to be a slight 
tendency towards greater specialization and development on the Spergulean 
type. The more massive and shorter suspensor occurring in the latter, 
with its small basal cell, is replaced by what may be a more labile 
filamentous one, in which the basal cell is greatly developed for absorption 
purposes, even to the producing of an haustorium as in Stellaria media . 
If in the development of the integuments we look upon the wing which 
characterizes some of the Sperguleae and results from the local hypertrophy 
of cells of layer 1 of the outer integument, as primarily functioning as 
a water jacket, but subsequently becoming modified for wind dispersal on 
