parru] | THE MECHANISMS OF FLOWERS. 379 
the accessible position of the honey. While in the flowers of Hrica 
_ tetralix, which hang vertically, great regularity prevails in the 
arrangement of the parts, the style occupying the axis of the 
- flower, and the anthers forming a circle symmetrically round it with 
ie heir orifices directed downwards, in the flowers of Calluna, which 
are almost horizontal, insects are liable to be dusted with pollen 
_ from above, as the style and stamens curve upwards and permit the 
insect to reach the honey only by way of the lower half of the 
flower. 
_ The larger bees, such as hive-bees and humble-bees, clinging 
_ with forelegs and midlegs to the outer side of the flower, weigh 
- it down into the vertical position ; then, hanging on below, they 
suck the honey and dust themselves with pollen, which would be 
_ sprinkled on them just as well and just in the same manner if the 
{ 
i 
| = 
19 
Fig, 124.—Calluna vulgaris, L. 
1.—O!d flower, seen from almost straight in front. 
2.—Younger flower, after removal of half of the calyx and corolla. 
8.—A stamen. , 
. be ones b, corolla; ¢c, appendages of anthers; d, nectaries; e, anther-orifice; f, filament 
g, style. 
| style and stamens were central as in JL. tetraliz. But the smaller 
bees and flies thrust head or proboscis from the front into the 
flower, and the upward curvature of the style and stamens causes 
the insect to enter by the lower half of the flower, and so to get 
dusted with pollen from above. 
As the bud opens, the anthers dehisce, and their appendages, 
which are set with squarrose hairs, diverge so far outwards that 
they cannot fail to be touched by the proboscis of any insect-visitor, 
and then, as the shock is communicated to the anthers, the pollen 
is shaken out. The style, which even in the bud overtops the 
_ stamens, grows very markedly after the flower opens, as the flower 
itself does (cf. 1 and 2, Fig. 124). Asa rule, it attains its full length 
- only after the anthers have completely shed their pollen, at which. 
time also the four-lobed stigma reaches its full development; but 
ae > day “Sorat E, = 
aoe eaten 
