50 Mr. A. Henfrey on the Progress of Physiological Botany: 
wliicli pre-exists and is visible in the nueleus before the intro- 
duction of the pollen-tubes into the ovules. Probably the im- 
pregnation is effected by the passage of the fertilizing fluid 
through the membrane of the embryonal vesicle,, this fluid being 
conducted to or deposited in the vicinity, or even on the surface 
of the latter. It is certain that the vesicle only acquires the 
power of development after the pollen-tubes have penetrated 
the coats of the ovule, and poured out the fluid which they con- 
tain upon it ; it dies without having shown any signs of growth 
when it is not moistened by the fertilizing fluid. 
The subsequent development of the embryonal vesicle shows 
itself first towards the base ; that is, at the point opposite to where 
the pollen-tube acts. All trace of this tube has disappeared by 
the time the enlarged embryonal vesicle begins to multiply its 
cells ; these become enlarged, particularly toward the base of the 
nucleus, finally reaching its walls, thus entirely filling its cavity, 
and even causing its rupture. The form which the embryonal 
vesicle ulteriorly assumes in the course of development is that of 
a constricted sac (the embryo-sac), within which, at the summit, 
many days after the epoch of fertilization, a greenish body makes 
its appearance, which is the true embryo of the new plant. 
Prom these facts, which are constant, it follows that the pollen- 
tube is not transformed into the embryonal vesicle*, because the 
latter exists already in the unfecundated ovule : still less is the 
pollen-tube developed into the embryo, for the embryo is not 
produced till long after, when the vesicle, very much enlarged, 
has become the embryo-sac. Moreover, the embryo is visible 
long before its diameter is equal to that of a pollen-tube, so that 
this latter cannot have become converted into it. 
^^In reference to CucurbitaPepo therefore,^^ says Amici, “I could 
be certain that Schleiden^s theory was incorrect, and, microscope 
in hand, offer direct demonstration. Analogy led me to believe 
that in other plants, where the action of pollen is necessary to 
fecundation, the opinion of the German botanist was inadmissible ; 
and I was the more strengthened in this conclusion, that in my 
numerous earlier researches in other plants, I had never seen the 
pollen-tube either lodge itself in the embryonal vesicle when the 
latter existed before fertilization, or itself become the embryonal 
vesicle.^^ 
After stating that although he had not extended his observa- 
tions to the families Orchidacece and Asclepiadaceccy he was induced 
not be confounded with the germinal vesicle, which is the first cell of the 
embryo. — Rep. 
* There is some confusion in the translations here: in the French this is 
given vhicule enihryonnaire ; hut Prof. Mohl uses the term Keimhldschen 
(germinal vesicle), with the synonym vesichetta germinativa. — Rep. 
