440 THE FERTILISATION OF FLOW ERS. [PART III. 
for sheltering and pointing out the honey. It differs from it only 
in certain apparently trivial points, viz. in the development and 
position of the style and stamens:—yet these apparently trifling 
differences greatly influence the mode of fertilisation and the 
possibility of self-fertilisation in the absence of insects. 
When the flower opens, the stigma is already well-developed ; 
it is provided with long papille, and capable of holding fast pollen 
applied to it. The anthers still remain closed. The stamens and 
style project forwards in a straight line from the flower and afford a 
standing-place for insects. In cold, windy, or rainy weather the 
flowers only open partially, and the anthers remain in contact with 
the stigma, leading to regular self-fertilisation. In warm sunshine 
the petals expand widely, coming to lie almost in one plane; the 
stamens are caused thereby to diverge more and more, and the’ 
anthers are thus removed to a distance from the stigma before 
Fic. 149.—Veronica Beccabunga, L.- 
-1.—Flower, viewed obliquely from above, so that the upper petal is foreshortened (x 8). 
2.—Corolla, after removal of the stamens, viewed from the front (x 3), 
3.—Flower, after removal of corolla and stamens, seen from the side (x 7). 
i a, calyx; b, corolla; c, stamen; d, ovary; e, style; f, stigma; g, nectary (green); h, protecting 
airs. 
dehiscing. Insects frequent the plant in considerable numbers. 
The most abundant visitor is a small species of Syrphidee, Syrztta 
pipiens, L.; hovering backwards and forwards in its jerky flight 
before the flowers, it suddenly alights on one; sometimes it 
settles on the projecting style and stamens, which bend beneath its 
weight, and creeps forward a step or two in order to thrust its 
proboscis (3 mm. long) into the tube (1 mm.) ; sometimes it alights 
on the anterior or on one of the lateral petals, and pulls down one of 
the stamens with its forefeet, until it can reach the pollen with its 
proboscis. It thus brings various parts of its body in contact with the 
anthers and stigma, and performs sometimes cross-fertilisation, some- 
times self-fertilisation. Most usually cross-fertilisation results, for the 
nsect alighting on the projecting style and stamens usually touches 
the stigma with the ventral surface of its body, already dusted with 
pollen. A smaller species of Syrphidee, Ascia podagrica, F., visits 
