95 
and Affinities of Trapella . 
here and there is its lumen visible (Fig. 37, sp.). That 
part which runs through the ‘diaphragm’ is early lost to 
view — though in Fig. 36, where the diaphragm is not yet 
lignified, the whole course of the suspensor can be traced. 
Finally, its lowest segment, which abuts upon the embryo, 
is lost with the elongating of the radicle — all that remains 
being some three or four cells attached to the apex of the 
radicle, and flattened, more or less, up against it (Fig. 37, sp 1 .). 
Before passing on to describe the vegetative organs of 
Trapella , it will be well to see in how far the conditions I have 
just described are to be regarded as unique. Our plant com- 
bines in itself so many unusual characters, any one of which 
would make it remarkable, that such a digression may be 
justified. 
The early stages of development of the ovule forcibly 
recall similar conditions in Hippiiris. At a very early stage 
the nucellus becomes invested in the ample single integument, 
and in it, as in Trapella , it becomes difficult to decide (older 
stages only being examined) whether the ovule is naked 
or not. Unger 1 , Schacht 2 , and Schleiden 3 all describe the 
ovule of Hippuris as being destitute of integument, and it is 
only recently that Fischer 4 has explained what really takes 
place. The embryo-sac mother-cell in Hippuris gives rise 
by transverse divisions to a row of four sister cells ; the three 
upper ones become quickly absorbed, — the nucellus — with 
the gradually enlarging embryo-sac — becomes enveloped in 
the developing integument. The behaviour of the epidermal 
cell lying at the top of the nucellus is peculiar ; it undergoes 
a longitudinal division, and then both cells undergo a number 
of transverse divisions, so that a small wedge-shaped cushion 
of cells is formed at the micropylar apex of the embryo-sac. 
The cushion plays the part of preventing the micropyle from 
1 F. Unger, Die Entwicklung d. Embryo’s von Hippuris vulgaris, in Bot. Ztg. 
1849, p. 329. 
2 H. Schacht, Entwicklungsgesch. d. Pflanzen-Embryon., Tab. xxv. fig. 12. 
3 Schleiden, Nova acta Acad. Leop. carol., vol. xix. Tab. v. fig. 69. 
4 A. Fischer, Zur Kennt. d. Embryosackentwicklung, &c., in Jenaische 
Zeitschrift, Bd. xix (1880), pp. 1 17-120. 
