Seed in the Scitamineae. 
l 7 
Calathea (Fig. 32), Myrosma , and Thalia (Fig. 26) show 
essentially the same structure, and this probably holds true 
for the other genera of the family. A section of the embryo- 
sac from an ovule of Thajia dealbata ready for fertilization 
shows the usual arrangement within the sac in a very clear 
manner (Fig. 27). 
The subsequent development of the ovule into the seed is 
such as to give the seed a truly campylotropous character, 
with a curved embryo-sac and embryo, in all but one of 
the forms examined. Certain features of this development 
have been described by Schleiden and Vogel (’ 42 ), by Gris 
(’ 59 , ’ 60 , ’ 60 a ), and by Eichler (’ 84 ) ; and the structure of the 
adult seeds has been discussed by Nees von Esenbeck (’ 31 ). 
But no connected account of the development has been given, 
nor can the deficiency be here supplied. In those genera 
whose flowers produce but a single ovule each ( Maranta , 
Thalia , &c.), the cavities of the sterile loculi become reduced 
to almost or quite imperceptible slits. The most satisfactory 
material at my disposal was that of Thalia dealbata , Fraser, 
to which the following account refers. 
The inner integument of the ovule, which, at an early stage, 
is but slightly unequal on opposite sides of the nucellus, and 
regularly curved (Fig. 25), soon begins to show a sharp in- 
bending at a point about opposite the base of the embryo-sac. 
This is often more marked on the short side of the integu- 
ment (Figs. 26, 32). The inbending continues as growth 
proceeds, with the result that the proportional distance from 
micropyle to chalaza is steadily reduced (Fig. 29). Meantime 
that part of the nucellus beyond the chalaza from the micro- 
pyle, with its integuments, is growing around the chalaza and 
curving downward (Fig. 29). Thus finally the chalaza is 
brought down close to the micropyle, as in seeds derived 
from truly campylotropous ovules (Fig. 30). During this 
process the embryo-sac elongates into the distal part of 
the nucellus, curving with its growth, until when fully 
developed the base of it reaches nearly to the chalaza, 
and the whole cavity assumes the form of a horse-sho.e. The 
c 
