6 
CONTRIBUTIONS TO BOTANY. 
cell, but most generally it becomes at length adherent to it 
after the excentric growth and apparent duplicature of the ovary. 
It is incorrect to say, regarding this development, that the two 
halves of this curvature are brought together till they unite in 
order to form the incomplete dissepiment in the manner above 
described. The circumstance which St, Hilaire mentions as the 
cause of the metamorphosis appears to me, on the contrary, the 
result of an agency which he has entirely overlooked, and to this 
source only the apparent duplicature can be referred. My ob- 
servations tend to the conclusion that it originates in a peculiar 
expansion and induration of the placenta within the cavity of 
the cell, to which cause alone is to be attributed this excentric 
growth of the ovary ; for, in those cases where the placenta does 
not become expanded, no such duplicature occurs. In the in- 
stance of Cissampelos, cited by St. Hilaire, it may be seen that 
the linear placenta first protrudes and extends itself at right 
angles with the side of the ovary, in the direction of the centre 
of the cell, and that the growth of the pistil on that side is at the 
same time arrested, in consequence of which the style and the 
base of the ovary preserve nearly their original distance, while 
the growing force is all expended on the opposite or dorsal side, 
thus producing the hippocrepical appearance described. By 
observing a section of a half-matured seed of Cissampelos, the 
development of the pseudo-dissepiment may be seen distinctly, 
when the nourishing vessels belonging to the placenta can be 
traced in the centre of this line of extension, reaching to its ex- 
tremity, like an imbedded umbilical cord, which is found in the 
same position after the whole has become ossified. There is no 
appearance of any duplicature of the pericarpial covering of the 
ovary, or its subsequent agglutination, as described by the 
eminent botanist referred to : it will be found to exist only in 
the endocarpial portion. The development, as I have explained 
it, is even more evidently demonstrated in the seed-vessels of 
Ueocarpus and Stephania, where the hippocrepical cell is formed 
round a flat, solid, orbicular disk, in the substance of which the 
nourishing vessels can be traced, as in the pseudo-dissepiment 
of Cissampelos. 
In a group which I have called Heterocliniece, the growth is 
somewhat varied : there, in the early stage, the ovule is attached 
as described in Cissampelos ; but the placenta, from which it is 
suspended, is like a broad oval disk upon the inner face of the 
cell ; and while the ovary continues to increase equally in all 
directions, the increment about the placentary space is somewhat 
less : this face of the ceU thus gradually assumes a convex shape 
inside, and the placenta swells into a globular figure, forming 
sometimes a hollow prominent chamber, within the cavity of the 
