structure and development of the flower. Hildebrand has ex- 
_ plained the mechanism of fertilisation (356). An insect, thrusting 
| its proboscis beneath the upper lip to reach the honey contained in 
| thespur, first touches with its back one of the stigmatic lobes; which 
project beyond the anthers and have their papillar surfaces directed 
parvum.) THE MECHANISMS OF FLOWERS. 465 
looked upon as the more primitive, from which the long-tubed type 
of V. spicata has been evolved by the agency of bees and sand- 
_ wasps. ‘Two different hypotheses suggest themselves for the origin 
of the genus Veronica. In the first place, the reduction of the 
stamens to two may be due to the development of the delicate 
_ pollen-shedding mechanism adapted for Syrphide, which we 
_ found to be best developed in V. Chamadrys and V. urticifolia ; 
just as in Salvia two stamens have certainly become aborted 
owing to the development of the special lever-apparatus in the 
others. According to this view, the oldest Veronicas are those 
which are adapted for Syrphide, the others, with short tube and 
flat limb, being developed from them by degeneration of the 
pollen-mechanism; and several species (¢.g., V. Beccabunga and 
V. aphylia) do seem to show such a degeneration. But it is con- 
ceivable that the ancestors of Veronica suffered reduction in the 
number of their stamens simply in consequence of gradual dimi- 
nution in size, as in Lycopus among Labiates, several Saginee 
among Alsines, small-flowered species of Ranunculus, Chasalea, 
and the small-flowered form of Stellaria media, L.; and that the 
| pollen-mechanism was subsequently developed in one section of 
the genus, In this case we must ascribe to a miscellaneous lot of 
Syrphidz and small bees the blue colour of the simpler Veronicas 
which are not provided with any special adaptations for Syrphide ; 
| for the Muscide and other Diptera, which also visit and fertilise 
| these simpler Veronicas, show no signs of favouring the production 
of a blue colour in any other instance. I see as yet no grounds 
_ for preferring either of these hypotheses to the other. 
Orv. LENTIBULARIE £. 
Utricularia, L.—Buchenau has investigated thoroughly the 
downwards ; immediately afterwards it comes in contact with the 
| anthers and gets dusted with fresh pollen. The stigma is irritable, 
folding upwards at once on being touched, so that pollen cannot be 
applied to the stigma of the same flower as the insect draws back. 
1 Botan. Zeitung, 1865, p. 63. 
