Seed in the Scitamineae . 
27 
shaped endosperm, which probably refers to a condition 
similar to that here described. It is probable that in the 
chalazal mass of Costus and the more striking diaphragm of 
Alpinia we have homologous structures of which a thorough 
study of Zingiberaceous seeds would bring to light other forms 
and grades of development. The thickened edge of the 
ingrowth in Alpinia seems to correspond to the rounded 
mass in Costus. In the former genus the chalazal mass has 
penetrated far into the seed, probably as the result of a down- 
ward extension of nucellar tissue on both sides of it. The 
use of these structures to the seed cannot be shown without 
studies on their germination ; but the possibility suggests 
itself that they may serve to afford firm points of support 
from which the embryo may exert its full pushing force upon 
the germinal lid at the beginning of germination. We have 
seen that the original differentiation in the Marantaceae 
extends inward from the base of the nucellus, with no 
accompaniment of the inner integument. In Costus , on the 
contrary, and apparently in Alpinia , this integument does 
limit the ingrowth. Whether all the tissue that forms the 
diaphragm in ASpinia is chalazal cannot be determined 
without a study of the development of the seed. But it 
does not seem likely that these structures in the Zingiberaceae 
can be strictly homologized with the perisperm-canals of the 
Marantaceae, though they may correspond to the chalazal 
portions of the latter. The suggestion above made as to the 
possible use of the chalazal mass in the former family is not 
so obviously applicable to the true perisperm-canals. 
We come now to the last of the Scitamineous families to 
be discussed, the 
Musaceae. 
In this family of four genera and comparatively few species, 
the members of the genus Heliconia present the most interest- 
ing and aberrant features. It is well known that several species 
of Musa develop seeds rarely or not at all. Of those which 
do so, M. Ensete , Gmel., has been studied by Wittmack (’68), 
