CONTRIBUTIONS TO BOTANY. 
205 
pedicel, which is furnished in like manner, and for the same 
purpose, with tracheal vessels. It is a far more reasonable in- 
ference than the gratuitous assumption of Fritsche, that the 
ovular tunics are generated by the spontaneous separation of the 
epidermis, whieh doubles itself up, so as to produce those tunics 
by its further expansion. 
After this early period, the further increment is very evident : 
the bottom of the channel I have described, with the budding- 
point, grows downward, becoming by degrees an oblong pouch 
with a broad, open mouth, suspended by the funicular point of 
its origin, at the same time that the nucleus and secundine 
enclosed in it grow upward] this continues till we have a com- 
plete and suspended anatropal ovule, ready for impregnation, 
at which period the papillary apex of the nucleus is exposed 
w'ithin the open mouths of the tunics; during this successive 
growth of the ovule of Amijgdalus, the apex of the nucleus never 
changes its zenithal aspect, while the chalaza as constantly points 
to the base of the cell ; there is no one-sided growth of the 
tunics, which grow equally upon all sides ; and there is no in- 
version of the nucleus or of its coats, according to the opinion 
generally entertained. In this development, all is beautifully 
contrived to attain by the most simple means the main function 
— the generation and perfection of the future embryo, for which 
purpose the apex of the nucleus is retained always in near prox- 
imity to the placenta by means of its short funicle ; and elose 
to this point we see, as Brongniart long since demonstrated, a 
lamellar plate, to which the funicle is attached, which plate, 
formed of a peculiar tissue, is terminated by a fringed border 
that overhangs the mouths of the ovular tunics : the articulated 
cells forming this process bear the name of telm conductrices, 
because they serve to conduct the pollinic influence to the point 
of the nucleus, by which means the embiyo-sac is impregnated. 
I mention here this point of structure, because the position of 
this fascicle of cells, in relation to the raphe, is sometimes an 
indication of importance, as I shall have to show in the case of 
the Rhamnacew. 
The mode of origin and the changes that take place in the 
growth of campylotropal and amphitropal ovules, with some 
modifications, are quite analogous to all that occur in the ana- 
tropal ; it is, therefore, unnecessary for our present purpose to 
speak of them ; but in regard to atropal ovniles, it is requisite to 
say a few words. Here the budding-point is at the very apex, 
not on one side of the placentary sheath ; the nucleus therefore 
makes its first appearance in a depression at that point, where 
also the secundine soon surrounds it, while the extremity of the 
sheath is extended by degrees to form the primine, — all three 
