184 
ORGANOGRAPHY. 
BOOK I. 
outer face to the lining of the cell of the anther, and by its 
inner face to the tissue formed by the pollen-cells. Three and 
a half or four lines of length in the flower-bud corresponded 
with a phenomenon altogether unexpected. At first the 
thick and succulent wall of each pollen-cell dilated, so as to 
leave a void between its inner face and the granules, not one 
of which separated from the mass, which proved that a force 
of some kind held them together. Shortly after four append- 
ages, like knife blades, developed at equal distances on the 
inner face of the pollen -cell, and gradually directed their edge 
towards the centre, so that they began by cleaving the granu- 
lar mass in four different lines, and finished by dividing it 
into four little triangular masses; and when the appendages 
met in the centre they grew together, and divided the cavity 
of the pollen-cell into four distinct cavities, which soon 
after rounded off their angles, and in a short time the little 
granular masses became spherical, like melted lead run into 
the hollow of a bullet-mould. The partition of the mass thus 
brought about by the appendages seems to me to indicate 
that at this period the mass was not protected by a special 
integument, and that the mutual adhesion of the granules 
was very weak. 
“ When things had arrived at this point, the portion of the 
tissue formed by the pollen-cells separated itself from the 
surrounding parts, and each pollen-cell became loose, gene- 
rally in the form of a square parallelopiped with rounded 
angles"; each little mass of granules gained a smooth, colour- 
less, transparent membrane, which was at first membranous, 
but afterwards became thick and succulent, and soon be^an 
to take on the characters peculiar to the pollen of the Gourd. 
The integument began to bristle with fine conical papillae; 
several roundish lids were traced out here and there on its 
surface ; it hardened, became opaque, assumed a yellow colour, 
ceased to grow, and attained its perfect maturity.’’ Mirbel 
adds to this highly interesting statement, that he finds in the 
generality of plants that the mode of forming the pollen is 
much the same as in the Gourd. 
Observations upon the same subject by Professor Mold 
were published at Berne, in 1834. The principal points of 
