210 
CONTRIBUTIONS TO BOTANY. 
ttuXt; 'porta, where the first development is upwards; and the 
latter from utto et irvkp, where it shows itself on the lower side 
of the sheath. In the first condition (where the micropyle 
points upwards), we have an ovulum a'natropum epip-ylum, or a 
pendent ovule with a ventral raphe; but where the same ovule 
becomes inverted by pressure, we have an ovulum epipylum 
resupinatum, or an ascending ovule with a dorsal raphe. Under 
the second condition (where the micropyle points downwards), 
we have an ovulum anatropum hypopylum, or an ascending 
ovule with a ventral raphe ; but when this becomes inverted 
by pressure, it is an ovulum hypopylum resupinatum, or a pendent 
ovule with a dorsal raphe. It often happens, where numerous 
ovules issue from a placenta of limited extent, that we have erect, 
horizontal, and pendent ovules all crowded together, some with 
a ventral, others with a dorsal raphe ; but it will be found that 
all are equally epipylous or equally hypopylous, the one series 
showing their raphes in their normal position, the second inter- 
mediately placed, while the third, by their resupination, have a 
dorsal raphe. Under the third condition, where the ovules are 
in collateral pairs, and where the earliest appearance of the 
nucleus is upon the lateral face of the placentary sheath, the 
raphes face one another, w’hether the subsequent direction of the 
ovule, by the pressure of growth, be pendent, horizontal, or 
ascending : this kind of development may be called aUopylar if 
in a single ovule, and heteropylar when in collateral pairs. 
Another consideration worthy of attention in the development 
of the ovule, is the position of the embiyo in regard to the seminal 
tunics, — that is to say, whether one of the faces of the cotyledons, 
or whether its margins be placed opposite the raphe : this point 
has seldom been regarded, except where the embryo is amphi- 
tropal or campylotropal, in which cases this position is known, 
from the radicle being said to be incumbent or accumbent in 
regard' to the cotyledons. This relative position is often a con- 
stant feature in certain families, while in others it is subject to 
much variation, as in RhamnacetE-, and the character is even 
sometimes variable in the same genus, as in Rhamnus. The 
position of the face of the cotyledon in regard to the axis of the 
ovary is a feature very distinct from that of its relation to the 
raphe ; and the two should not be confounded together : thus in 
Rhamnus catharticus the raphe is dorsal, both with respect to 
the axis of the ovary and to the embryo ; in R. chlorophorus it 
is dorsal with regard to the embryo, but lateral as respects the 
axis of the ovary. In most instances throughout the Rhamnacea 
the embryo is incumbent with respect to the ovary, one of its 
cotyledons being posterior, the other anterior, in regard to the 
axis ; but it is accumbent in regard to the raphe, which skirts 
