CHAP. II. 
EMBRYO. 
255 
“ Thus in Sea-wrack (Zostera marina), of which the em- 
bryo is an oblong almond-shaped body with a cleft on one 
side, in the cavity of which a long flexuose process is placed, 
the latter is the plumule, and the former at one end the 
cotyledon, and the radicle at the other ; in Ruppia maritima, 
whose embryo is an oblong body, cut suddenly off at one end, 
on which a sort of curved horn crouches, the latter is the 
plumule, and the former chiefly cotyledon ; and so in Frog-bit 
(Hydrocharis morsus ranae), the embryo of which is an oblong 
fleshy kernel with a hole on one side, in which there lies a 
short cylinder, the latter is the plumule, and the former the 
cotyledon.” 
The Acotyledonous embryo is not exactly, as its name 
seems to indicate, an embryo without cotyledons ; for, in that 
case, Cuscuta would be acotyledonous. On the contrary, it 
is an embryo which does not germinate from two fixed in- 
variable points, namely the plumule and the radicle, but in- 
differently from any point of the surface ; as in some Araceae, 
and in all flowerless plants. See Mohl, Bemerlmngen iiber die 
Entwicklung und den Ban der Sporen der Cryptogamischen Ge~ 
wdclise : Regensb. 1833. 
For further illustrations of the embryo, consult Plate VI. 
and the explanation of its figures. 
The direction of the embryo is either absolute or relative. 
Its absolute direction is that which it has independently of 
the parts that surround it. In this respect it varies much in 
different genera; it is either straight (Plate VI. fig. 5.), 
arcuate (fig. 9.), falcate, uncinate, coiled up (fig. 8.) [cyclical)., 
folded up, spiral (fig. 19.), bent at right angles (Plate V. 
fig. 28.) [gnomonical., Link), serpentine, or in figure like the 
letter S [sigmoid). 
Its relative position is determined by the relation it bears 
to the chalaza and micropyle of the seed ; or, in other words, 
upon the relation that the integuments, the raphe, chalaza, 
hilum, micropyle, and radicle bear to each other. If the sacs 
of the ovule are in no degree inverted, but have their com- 
mon point of origin at the hilum, there being (necessarily) 
neither raphe nor chalaza visible, the radicle will in that case 
be at the extremity of the seed most remote from the hilum. 
