a 
160 THE FERTILISATION OF FLOWERS. [PART II. 
Experiments on artificial pollination and the growth of the 
resulting seeds, which Hildebrand afterwards instituted with two 
trimorphic species, O. Valdiviana and O. Regnelli, Miquel, led to 
results similar to those of Darwin in the case of Lythrum Salicaria. 
They showed (1) that productiveness is greatest, or exists only, 
after legitimate fertilisation ; (2) that both parent-plants influence 
the fora of the offspring; (3) that pollen-grains from stamens of 
equal length are of the same size, and diminish from the tallest to 
the shortest anthers. 
Hildebrand gives a figure of the trimophic flowers of Oxalis 
gracilis, Jacq. (348). H. v. Mohl has described the cleistogamic 
flowers of O. acetosella (531). 
Tribe Balsaminee. 
: 
Impatiens Balsamina, Tilo.—In younger flowers the anthers lie — 
upon the still closed stigmas, and dust their pollen upon the backs 
of insects (bees) which dip their proboscides into the spur; in older 
flowers, when the crown of anthers has withered, the outspread 
stigmas come in contact with the same parts of the bee. 
H. v. Mohl has described cleistogamic flowers in Jmpatiens 
Noli-me-tangere, L., and in North American species (531). 
On cleistogamy in Impatiens fulva, Nutt, see M. A. Loche 
(417); on cleistogamy in both species, see Bennett (72, 79). 
Impatiens parviflora, D.C., according to Bennett, never produces 
cleistogamic flowers, but according to Henslow it is liable to 
spontaneous self-fertilisation. 
North American species of Jipatiens are visited by humming- 
birds (164). 
Orv. RUTACE A, 
84. RUTA GRAVEOLENS, L.—The most prominent features of 
the flower have been described by Sprengel. 
A fleshy disc situated beneath the ovary secretes ines in 
eight to ten glands upon the bases of the stamens, sometimes in 
larger glands between these, besides producing small drops over its 
whole surface: the honey lies quite exposed and freely accessible. _ 
The strong scent and the greenish-yellow colour of the flowers 
seem able to attract only Hymenoptera and Diptera, the latter in — 
very great numbers. The stamens, when the flower opens, lie 
two in each of the petals, which are hood-shaped and spread out 
horizontally. According to Sprengel, two stamens on opposite 
sides of the flower rise up simultaneously, bending inwards so that 
