AND ON POLYEMBRYONY IN THE HIGHER PLANTS. 9 
to give up our old and so generally adopted ideas on the sexes 
of plants,—those, namely, according to which the fructifying 
principle resides in the contents of the pollen-grains, and the 
anthers are therefore to be compared to the male sexual organs 
of animals. With these views, and the facts above communi- 
cated on the first formation of the embryo, the origin of hy- 
brids among plants will appear to us quite intelligible. 
There is, moreover, another fact which perhaps speaks quite 
as decidedly against the view of M. Schleiden and his followers, 
in addition to the relation of hybrids, though I must confess 
that, unfortunately, I myself have never noticed this phzno- 
menon; I mean here Mr. R. Brown’s observation of ramified 
embryonal-funiculi, where the extremities of the branches af- 
forded the rudiments of embryos, and to which I shall subse- 
quently again revert. 
Many years ago M. de Mirbel* advanced the position that 
impregnation in plants (at least in the higher orders) is no- 
thing more than the grafting of the male cell upon the female. 
I believe I may conclude from this remarkable expression, that 
De Mirbel already at that time (1833) had observed the union 
of the pollen-tube with the embryo-sac. Now, the comparison 
of this union with a graft is not indeed quite correct, for that 
which is grafted, as is well known, continues its further growth 
without considerable change—in general without any change at 
all; but this is what De Mirbel by no means intended by this 
expression, for he and Mr. Robert Brown are both defenders of 
our old views on the sexes of plants. 
We now come to the consideration of the formation of the 
embryo in those cases where it is formed in the interior of the 
cavity of the nucleus without a separate (special) embryo-sac; 
this occurs most frequently in Monocotyledons, and also not 
very rarely in Dicotyledons. M. Schleiden at the commence- 
ment mentioned the process of impregnation in the Orchidee 
principally in proof of his new view, namely, that the germ is 
carried to the embryo by the pollen-tube into the ovule, where 
it then undergoes further development; however, although the 
process is somewhat different in this case, on account of the want 
of an embryo-sac, yet the impregnation agrees in the main with 
the act of fructification in the cases already cited with an embryo- 
* Complém. des Obs. sur la Marchantia polymorpha, p. 51. 
