PART 111. | THE MECHANISMS OF FLOWERS. 269 
honey through one of the lateral entrances ; in either case it gets 
‘dusted with pollen —in the former case on the lower surface of 
its body, in the latter on both sides of its head. The pollen seems 
_ to be rendered adherent by the sticky contents of the colourless 
_ spheres (i, 4) which border the narrow strips of pollen; they must 
come in contact with the head or ventral surface of the insect just 
as the pollen itself does. 
_ In the female flowers the pistil rises up from the middle of 
_ the cup, and splits into three divergent branches, broad at the 
_ ends, lobed, and set with projecting points. These touch the head 
_ or ventral surface of an insect-visitor with their papillz and retain 
the pollen that may be brought. As the male flowers are twice 
' 
? 
i 
it 
‘ 
Fic. 89.—Bryonia dioica, L. 
1, 2.—Anthers of the male flower. The arrows point to the lateral entrances. 
3.— Male flower, in longitudinal section, magnified. mn, nectary. 
4.—Ditto, more magnified, from above. 
a, filament; p, pollen; k, colourless spherules. 
is large as the female, they are generally the first to be noticed and. 
visited. 
To push the head between closely approximated parts of a 
| flower is a characteristic action among wasps and bees, which 
acquire the habit in constructing the chambers for their young. 
_ The honey is easily accessible to the thin proboscis of a butterfly, 
_ and the pollen of the male flowers is available to flies and beetles ; 
_ but the latter can have no part in the process of fertilisation since 
they confine their visits to male flowers. 
_ Visitors: A. Hymenoptera—(a) Apide: (1) Andrena florea, F. 2? ¢ (A. 
' rubricata, Sm.), by far the most abundant visitor of this plant, s. and c.p. ; it 
/ seems to restrict itself exclusively to this plant ; (2) A. nigroaenea, K., freq., s. 
, and c.p.; (3) A. fulvicrus, K. ¢,s.; (4) Halictus sexstrigatus, Schenck, ?, 
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