vari] THE MECHANISMS OF FLOWERS. 347 
t Seabular parts of the florets, but since these bend over at their upper 
ends more and more the nearer they stand to the edge and diverge 
- outwards around the capitulum, a capitulum in full ‘bloom ems a 
red circular area 20 to 30 mm. in diameter. When a floret opens, 
its style has the position represented in Fig. 115, 3 ; its two stigmatic 
divisions are closely appressed and inclosed in the upper part of 
“the cylinder formed by the coherent anthers ; a ring of hairs (Fig. 115, 
3, 4, ¢), directed obliquely upwards and tiaching the inner wall of 
the anther-cylinder all round, has swept all the pollen into this 
“upper part of the cylinder, so that the branches of the style are 
closely packed round with pollen. If the flowers in this stage are 
left untouched for a day or two in a room, the terminal valves of 
. ‘the anther-cylinder. separate, and a little pollen appears between 
em atthe top. But if one now touches the filaments with a needle 
‘or a sharp pencil (as in a natural condition the insect’s proboscis 
loes), a great quantity of pollen is in a short time seen to emerge, 
and the anther-cylinder is seen to be drawn down so far by the 
contracting filaments that the branches of the style protrude 
above. Since their whole outer surface is covered with small hairs 
directed obliquely upwards, they remain, after emerging from the 
anther-cylinder, so thickly coated with pollen, that they are not 
Tecognisable as branches of the style until the pollen has been 
brushed away. 
Gradually the style grows up still further beyond the anther- 
cylinder (Fig. 115, 2); the edges (set with stigmatic papillz) of the 
inner surfaces of the two branches of the style bend outwards 
, 2); and the ends of these branches also gape asunder, so that 
‘here also stigmatic papille are exposed to the touch of insect- 
“visitors. Spontaneous self-fertilisation can under these circum- 
/ stances not occur, and self-fertilisation can only be brought about 
| by insects, if, at the time when the stigmatic papille become 
: ‘exposed, the outer surfaces of the branches of the style or the ring 
| of hairs are still dusted with pollen ; on the other hand, if sufficient 
insect-visits occur, cross-fertilisation is fully insured. Although 
‘the expanded portion of the corolla is longer than in most of our 
other native Composite, and many short-lipped insects (sand-wasps 
sand the majority of flies) are therefore excluded from the honey, 
yet, in consequence of the great amount of its honey, it is one 
of the most frequented forms. Various species of bees come in 
numbers and pay lengthy visits to its capitula, and in creeping 
between the anther-cylinders and styles protruding from the florets, 
they bring not only their under-sides, but the greater part of their 
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