- 390 THE FERTILISATION OF FLOWERS. [parr ur. 
red colour of the filaments, or (2) by the larger size of the petals, 
or (3) in both characters together, or in addition (4) by a slight 
red colouring in the base of the corolla, or still further (5) by a 
slight extension of the style beyond the longer stamens. All such 
intermediate stages between the extreme forms occur in the same 
localities, and not unfrequently even on the same plant. 
These forms of Lysimachia vulgaris form another illustration 
of the law, exemplified in so many previous cases, that while it is 
of advantage to the plant when sure of insect-visits to be capable 
of cross-fertilisation only, it is above all important that, where 
insect-visits are rare, the plant shall be capable of reproducing 
itself by self-fertilisation. As 
I have not discovered honey in any of the forms of this plant. 
The flowers are visited regularly and persistently by pollen-seeking 
insects, and sometimes by honey-seeking insects which fly away 
after a few vain attempts to find honey. 
A. Hymenoptera—(a) Apidw: (1) Macropis labiata, Pz. 2 ¢, rather ab., — 
especially the females, on the sunshine-loving form of the plant. I found the 
females as a rule only on flowers of this plant, diligently sweeping the flowers 
and piling large masses of moistened pollen on their hind legs. I am still 
unable to decide where they got the material to moisten the pollen with. I 
should suppose that they bored into the succulent tissue of the flower, were it — 
not that the mandibles are blunt and fringed at the end : perhaps the sharp 
points at the end of the short blunt tongue do this work, which usually belongs 
to the mandibles. (2) Halictus zonulus, Sm. ¢, scarce ; (83) Andrena denticu- 
lata, K. 3, scarce; (b) Vespide : (4) Odynerus parietum, L. 3, scarce (the last 
three had obviously visited the flower in the vain hope of honey). B. Diptera 
—Syrphide : (5) Syritta pipiens, L., fp. on the self-fertilised shade-loving 
form ; (6) Syrphus balteatus, Deg., f.p. 
Lysimachia nummularia, L., is almost always sterile (Darwin, 
No. 158), perhaps because all the examples in the same neighbour- 
hood come from the same stock (cf. Eug. Warming, No. 762). | 
Lysimachia thyrsiflora, L., is proterogynous (762). 
Centunculus minimus, L., is regularly self-fertilised, according 
to Ascherson (10); it could hardly be otherwise, to judge from the — 
inconspicuousness of the flowers, 
Anagallis arvensis, L., and A. cerulea, Schreb.—Delpino. 
is of opinion that A. cwrulea and arvensis were originally 
two forms of a single dimorphic species, which became in- — 
dependent (“divorzio di due forme reunite originariamente sovra 
una pianta dimorpha;” No, 172, p. 45); but as yet this view is 
without proof. 
