554 
APPENDIX. 
[B. 
The same explanation of structure applies to the seeds of 
Piperacese and Saururus; and other instances occur of the 
persistence either of the membrane or of the substance of 
the amnios in the ripe seed. 
It may be concluded from the whole account which I 
have given of the structure of the ovulum, that the more 
important changes consequent to real, or even to spurious 
fecundation, must take place within the nucleus ; and that 
the albumen, properly so called, may be formed either by a 
deposition or secretion of granular matter in the utriculi of 
the amnios, or in those of the nucleus itself, or lastly, that 
two substances having these distinct origins, and very dif- 
ferent textures, may co-exist in the ripe seed, as is probably 
the case in Scitaminese. 
On the subject of the ovulum, as contained in an ova- 
rium, I shall at present make but one other remark, which 
forms a necessary introduction to the observations that 
follow. 
On the Structure of the female Flower in CycADEiE 
and CoNiFERiE. 
That the apex of the nucleus is the point of the ovulum 
where impregnation takes place, is at least highly probable, 
both from the constancy in the appearance of the embryo at 
that point, and from the very general inversion of the nu- 
cleus ; for by this inversion its apex is brought nearly, or 
absolutely, into contact with that part of the parietes of the 
ovarium, by which the influence of the pollen may be sup- 
posed to be communicated. In several of those families of 
plants, however, in which the nucleus is not inverted, and 
the placentse are polyspermous, as Cistinese it is difficult 
* This structure of ovulum, indicated by that of the seed, as 
characterizing and defining the limits of Cistinese, (namely, Cistus, 
