58 Mr. A. Henfrey on the Progress of Physiological Botany: 
low, so that this cell (the germinal vesicle) is thus changed into 
an ovate body composed of three or four cells lying one above 
another. Of these secondary cells the two situated at the two 
rounded extremities are of greater diameter than those lying in 
the middle. Each of them contains a nucleus. 
Contemporaneously with the growth and division of the ger- 
minal vesicle, the protoplasm collected at the base of the embryo- 
sac forms itself into an irregular mass of roundish parenchymatous 
cells, of which some frequently project into the central unoccupied 
space of the embryo-sac, and even come in contact with the lower 
end of the germinal body. In the course of the next two or 
three days the germinal body increases in size so much that it 
gradually comes to occupy the whole embryo-sac, displacing the 
cells contained in its lower end ; its diameter is now about ^^th 
of a millimetre. At the same time a longitudinal septum is 
formed in the lowest cell of the germinal body, and soon after 
in the next above it. 
The lower end of the pollen-tube, the swollen, blind extremity 
of which is about of a millimetre in diameter, undergoes no 
change during this time. 
The lower cells produced by the division of the germinal ve- 
sicle grow faster than the upper, so that the form of the struc- 
ture is changed from ovate to clavate, the larger end downward. 
The cells of the upper end now grow upward and form trans- 
verse septa, finally passing out through the canals and the mouth 
of the ovule, as described by Amici, in the shape of a confervoid 
filament or articulated hair. Originally the end of the pollen- 
tube lies beside this, so that they cannot be mistaken one for the 
other. Simultaneously the cells of the lower end multiply and 
form an enlarged body, the cells of which are filled with a dense 
mass of granules; this opake cellular nucleus is of course the 
embryo. The hair-like prolongation of the upper end is distin- 
guished both by its cylindrical form and the transparency of its 
cells, which merely contain watery fluid wfith a small quantity of 
finely granular protoplasm and a cell-nucleus. When the ger- 
minal vesicle has thus become developed into the embryo and its 
filamentous appendages, the pollen-tube disappears, apparently 
by absorption. At the time when the filamentous appendage 
becomes elongated, a deposit of spiral fibres occurs in the cells of 
the outer coat of the ovule, and the seed proceeds rapidly toward 
maturation. 
Comparing these observations with Amici^s, it will be seen that 
they only differ in one point of very small importance, which re- 
fers to the mode in which the embryo-sac displaces the nucleus. 
Prof. Von Mohl deduces from them the conclusion, that we must 
