2 6 ON THE FERTILIZATIOjr
5. Total height of flower from base of pedicel to stigma 1-28 mm.
Heigbt from base of pedicel to top of ovary 0-912 mra.
Greatest brotidtb of Sower, including the periauth 0'484 mm.
Length of style along inner side 0-427 mm.
6. Average measurements of large pedicellate flowers—
Total height from base of pedicol to stigma 1-5 mm,
Height froia base of pedicel to origin of perianth 0'4 to 0-5 mm.
Height from origin of perianth to ovary 0-25 mm.
Height from base of ovary to its summit 0-48 mm.
Length of style along inner side 0-48 mm.
Breadth of stigma 0-2 mm.
Considerable variations exist ia the total heights of the flowers, these being mainly
determined by the absence or presence of a pedicel (Plate II, figs. 2, i), but also to some degree
by variations in the lengths of the styles. The gamophyllous perianth has three iobcs, a
broad one being situate opposite to the side oi stylar attachment, and t-wo narrow ones
passing upwards, one on each side of the base of the style (Plate II, fig. i). The tips of all
three lobes rise above the level of the summit of the ovary, and that of the large one curves
over it. The style is attached practically to one side of the summit of the ovary, -which is
flattened or only slightly convex (Plate II, fig. 4 ; Plate IV, fig. 19). The stigma is trumpetshaped,
or in some cases furrowed. The bottom of the hollow communicates by a small
orifice with a canal -which descends through about three-fourths of the length of the style,
narrowing as it does so and coming to a pointed end at some distance from the ovary
(Plate IV, fig. 19). The lo-wer fourth of the style is solid throughout. Its external surface
is quite smooth throughout. The stigma and the upper portion of tlie styles have a more or
less pronounced pink tint, due to the presence of varying numbers of coloured cells; the
ovary and perianth are colourless.
The ovary externally is broadly oval, and its cavity is almost circular (Plate IV, fig. 19).
Its -walls vary greatly in thickness in different parts, being much thickest along the side
of stylar insertion, thinning off thence in every direction, and becoming very thin on the side
opposite to the style. The following figures show the thi(!kuess of the walls at different
points in one flower:—
Thictneas at origin of the inner side of the style 0'05 mra.
Thiokness over the middle of the summit of the ovary 0-04 mm.
Thickness over s-iirfaee of ovary on the side opposite that of stylar
attachment O'Olo
Along the inner side of the base of tlie style and the neighbouring areas of the ovarian
-wall the epidermal cells are shortly columnar and have somewhat thickened walls (Plate IV,
fig. 19). Further out they become thin-walkd and squarish, and over the rest of the surface
except the basal portions, where they again tend to become cylindrical, they are more or less
flattened. There are four distinct layers in the thickness of the walls (Plate V, fig. 22).
Immediately beneath the outer epidermis is a single stratum of flattened cells, which at this
stage stain like the epidermal ones; beneath it is a thick layer of four cr five superimposed
strata of small cells, which take a pink tint with picrocarmine, and within this is the inner
epidermis, the flattened cells of which, like those of the outer epidermis and hypodei-mis, are
stained yellowish.
OP PICUS ItOSBTJEGHII. 27
The ovule presents a more or less rounded outline, due to the great thickness of the iuniole
and o£ the seeundine o£ the funicular side at this stage of development (Plate IV, fig. 19).
The free portion of the fanicle is very short, being only about 0-01 mm. in length by 0 09
tnm. in breadth.
It arises immediately beneath the base of the style, and the flbrovascular bundle curves
abruptly downwards, andis continued in a raphe to the base of the more or less erect nucellus
(Plate IV, fig. 19). The thickness of the seeundine along the raphe and the stylar aspect of
the upper part of the nucellus is very great; so great, in fact, as not to suggest an integument,
but a solid mass of tissue into one side of which the nuceUus is insotled. In a case in which
the thickness was measured, at the point of greatest depth it was 0-04 mm. The entire
ovule iu this speeimen was 0 20 mm. in length by 0-15 mm. in breadth, and the nucellus had
a height of 0-1Ó mm., a greatest breadth of 0'09 mm., and a breadth in the mioropyle of
0'06 mm. The seeundine, especially on the funicular aspect, appears to be hut loosely
connected superiorly with the nucellus, and tends to separate more or less from it towards the
micropyle (Plate IV, fig. 19). The nucellus is erect or slightly inclined outwards, and is
practioslly straight, its apex facing the under surface of the wall of the top of the ovary (Plate
IV, £g. 19). The micropyle, as the measm-ementi given above show, is relatively very large.
The epidermal stratum of the nucellus presents a general resemblance to that of the ovules in
the normal female flowers, being thin and composed of flattened cells over the greater part
of the surface, and forming a eonspicnously thickened mass which plugs the oriñce of the
micropyle. This plug is not, however, so thick as in the female flowers, and is apparently
also of looser texture than in them. Within the epidermal coat a stratum of loose tissue
IS present around the embryo-sac. It also generally resembles that present in the ovules
of the normal female flowers, but at the same time it does not form a deñnite dense
cap over the apes of the embryo-sac as it does in them, there being merely a certain
thickening of the common loose tissue there.
B.— Ohamctirs of gall-Jlowen suilequrM to occejj ofimeets to the receftade.
The following figures show the measurements of a gall-flower s c Q ............^...siu^o Ü. gilii-iiuwer shnortiliy aafirte r access^ of
insects to the receptacle, and containing an insect's ovnm which as yet showed ,
Total beiglit.froia base of pedicel to summit of the stigma . . . 2'850 mm
Height fi'om base of pedicel to summit of ovary 3.7075 ram.
Length of style along the innei' side 0'4275 mm
Length of pedicel below the origin of the pearinth 1-282
Transverse diameter of ovary 0'5700
Ovules at this stage have an obovate form, and when' removed fi-om the ovaries and
collapsed, due to extraction of the fluid from the interior of the embryo-sac in the course of
preparation, measure about O'S x 0'6 mm., and in their normal condition about O'S x 0 57
From the above figures it is evident that the deposition of ova causes a very rapid and
considerable increase in the si« of the flowers generally, the increase being invariable
in the ovaries and ovules, but in many cases occurring in the axis also, and determining very
conspicuous elongation of the pedioels. The enlargement in the ovules appears for the
most part to be due to mere extension of pre-existent cell elements under the influence of
distention of the emiryo-sao, due to a lai-ge accumulation of fluid within its cavity • but a