OF THE OVULE OF CHRISTISONIA. 577 
differences from Orobanche, it is interesting to show the homo- 
geneity which exists in the reproductive organs of the two 
genera. 
Hofmeister *, in 1859, described the structure of the embryo-sac 
of Lathrea squamaria at certain stages of its development, but 
did not offer much detail on the subject. 
During the course of my work I have had considerable obstacles 
to put up with in the character of the ovules in this plant. Their 
small size, their disposition on the placenta, and the deep purple 
coloration which, in the two species of which there was plentiful 
material, disfigured the whole plaut, rendered the determination 
and position of the nuclei in the various parts of the ovule a 
by no means easy task. 
Structure of the Ovary. 
As stated in my former paper, the ovary of Christisonia is uni- 
locular, with two bipartite placentas. In one of the species 
(C. neilgherrica, Gardn.), however, there is a slight modification, 
the lower portion of the ovary being bilocular owing to the fact 
that the placentas from opposite sides meet and fuse in the 
centre, whereby the ovules acquire an axile placentation; in the 
upper part of the ovary the placentas again separate, and the 
ovary becomes unilocular. The ovary of Orobanche differs from 
the plant under consideration in having four or five simple 
placentas. 
The ovule is anatropous in form, and is attached to the placenta 
by a rather long funicle, so that it does not lie perfectly hori- 
zontal in the ovary, but takes up a more or less oblique position. 
Its single integument consists of two layers, of which the outer- 
most has very much larger cells than those of the inner layer, 
which latter in the mature seed becomes no longer recognizable 
as such. The cells of the outer layer of the integument, which 
eventually forms the testa of the seed, are characterized, as in 
Orobanche, by having excessively thickened inner and lateral 
walls, which are lignified. The jinner walls, viz. those bordering 
on the inner layer of the integument, have curious wide pits at 
intervals, which give them quite a characteristic appearance. 
The nucellus is two or three layers of cells in thickness. 
* * Neue Beiträge z. Kenntniss d. Embryobildung d. Phanerogamen,' 1859. 
BOTANY, VOL. XXXI. 2T 
LINN. JOURN. 
