AND ON POLYEMBRYONY IN THE HIGHER PLANTS. 7 
remains within the apertures of the nucleus and the tunics; or 
as in Ceratophyllum, where the vesicular swelling projects out 
of the apex of the ovule, and exhibits here and there other cy- 
lindrical excrescences, of which I have seen three, and even four. 
Although it is almost a rule in the genus Mesembryanthemum, 
that the end of the pollen-tube applies itself, in the process of 
impregnation, laterally to the apex of the embryo-sac, yet it 
even here sometimes occurs that the germinal vesicle is formed 
at the apex of the embryo-sac, and then grows into it, as, for in- 
stance, takes place regularly in Alsine media. Accordingly these 
differences appear not to be very essential; and if we see in the 
conjugation of the Conferve conjugate, some Mucedines { Faden- 
pilze|, and other Alge, an analogue to the act of impregnation 
in the higher plants, in which we most undoubtedly are justified ; 
so in like manner do we find in these exactly the same differ- 
ences, which, however, are here entirely unessential. In Con- 
Serva bipunctata the well-known mode of conjugation usually oc- 
curs, in consequence of which the spore is formed in the in- 
terior of one of the conjugated joints; at times, however, we 
meet with entire masses of this Conferva, in which the spore 
constantly arrives at development in the obliterated warts of 
fructification, quite as in Syzygites, and as we have observed it 
in Closterium, &c. 
Now after the germ-vesicle has been formed in consequence 
of the act of impregnation, it proceeds in its development, which 
again varies in the different genera and species of plants. In 
general the germ-vesicle expands in length, growing into the 
depth of the embryo-sac, and usually represents a cylindrical 
tube [Schlauch|, from whose end a simple globular cell then 
separates [abschniirt|, which is the young embryo. The other 
remaining part of the cylindrical tube forms the funiculus of 
the embryo, and adopts in different plants very various forms 
and structure ; frequently it remains like a simple string of rows 
of cells ; frequently individual parts swell to a greater or less 
size in a vesicular form*, and often the funiculus of the em- 
bryo is transformed into one thick cellular cord. The various 
drawings which I have given in the work above cited afford 
sufficient explanation relative to the formation of the rudiment 
of the embryo and its separation from the funiculus; and, 
* See the drawings of Capsella Bursa-pastoris and Alsine media in my Vege- 
table Physiology, vol. iii. pl. xiii. 
