Origin and Development of the Vegetable Embryo. 53 
creased in size ; the tegmen still projects beyond the testa, but 
the nucleus is covered by both membranes, and has not percep- 
tibly enlarged. But the granular fluid formerly collected at its 
upper extremity has become converted into a cell, which is the 
embryonal vesicle {vesichetta embryonale), and is filled with a 
similar fluid. 
Another epoch succeeds the withering of the flower. The 
stigma (or stigmata, for there are three) show by their decay that 
they are dead. The pollen-mass has already acted upon them ; 
the pollen-tubes, after having traversed their tissue and that of 
the style, have become prolonged into the evidently enlarged 
ovary. The ovule has equally undergone a change ; the tegmen 
no longer projects beyond the testa; it is contained within it. 
The nucleus retains its relative situation within the tegmen, and 
the embryonal vesicle, which is always adherent to its upper end, 
exhibits the granular fluid, previously distributed throughout its 
cavity, collected toward its base. [Prof. Von Mohl, in his trans- 
lation, here explains that the author, by the apex of the embry- 
onal vesicle, signifies the end corresponding to the apex of the 
nucleus ; and by the base, the end hanging free in the nucleus ; 
an explanation rendered necessary by the anatropous condition 
of the ovule.] The ovule is now exactly in the condition to re- 
ceive the influence of the pollen. The pollen-tube enters by the 
orifice of the testa, and its progress into the interior of this first 
coat is as visible as though no membrane intervened ; its passage 
through the canal of the tegmen is not always so clear, for either 
from an actual narrowing of the canal, or from an optical illusion 
resulting from the cylindiical form of the cells of the tegmen 
which bound it, the diameter of the tube appears to be much 
diminished. But there can be no doubt of its prolongation when 
its extremity is clearly seen to pass out from the narrow canal of 
the tegmen and into the cavity of the nucleus. The question- 
now is, does it push back the pre-existing embryonal vesicle in 
order to enter its cavity ? To this Prof. Amici replies, most de- 
cidedly, no. The pollen- tube merely comes in contact with the- 
side of the upper part of the embryonal vesicle, and remains ad- 
herent to it, finally withering and disappearing. The end of the 
pollen-tube, filled with a greenish and granular fluid, contrasts 
distinctly wfith the embryonal vesicle, 'which in the upper part, 
where it is in contact with the tube, is filled with a limpid fluid ; 
while below, where the pollen-tube never reaches, it contains a 
white granular fluid. This condition of the circumstances, the 
author says, is so constant, that he can tell at a glance v^hether 
an ovule has been fertilized or not. Whenever the embryonal 
vesicle presented itself with the pollinic appendix just spoken of, 
he was certain of finding the tube engaged in the coats of the 
