PART III. | THE MECHANISMS OF FLOWERS. 367 
which is rubbed off by the hairy bodies of insect-visitors until it is 
_ exhausted ; meanwhile the hairs of the brush gradually shrivel. - In 
: the pnd. stage the three divisions of the style separate and curve 
_ backwards, exposing their inner surfaces covered with stigmatic 
: - papillze (st) to be touched by insect-visitors. In case of sufficient 
insect-visits, cross-fertilisation, and, as in every case of marked 
_ proterandzy, fertilisation of older flowers with the pollen of younger, 
_ is inevitable. 
+ In Campanula, when insects have not visited the flower to 
- sufficient extent, the stigmas usually bend further backwards 
Fic. 118.—Campanula pusilla, L. 
ie hi eal 
A.—Section of young bud. 
B.—Essential organs of a bud about to open. 
C.— Essential organs of a flower, in first (male) stage. 
D.—Ditto, in second (female) stage. (x 4. 
sd, expanded bases of the filaments, fringed with hairs, which guard the honey ; grb, brush upon 
ete sty le ; grb’, ditto, after its hairs have shrivelled up. 
oh NG 
until self-fertilisation is effected. The papillose end of the stigma 
either comes in immediate contact with the pollen still adhering 
to the upper end of the styles, or pollen falls of itself upon the 
‘papillee of the recurved portion. It is clear from its wide, bell- 
shaped corolla, that Campanula is specially adapted for humble- 
bees, but the flowers in the various species are visited by many 
other insects, chiefly bees. Many insects find shelter from rain 
and also spend the night within the flowers ; and some confine their 
visits mainly (Cilissa hemorrhoidalis, species of Chelostoma) or 
almost exclusively (Halictoides dentiventris) to species of Campanula. 
