406 THE FERTILISATION OF FLOWERS. [PART IIT 
petals, and offered their insect-visitors either honey lying fully 
exposed in the angle between ovary and corolla, or pollen only. 
In either case the most various insects were admitted, and they 
performed cross-fertilisation (as in G. /wtew) casually and irregularly, 
so that the power of spontaneous self-fertilisation could no more 
be dispensed with than in G. lutea. 
In both main divisions, as the nectaries became more perfect, 
bees and especially humble-bees proved themselves the most 
efficient cross-fertilisers; and in relation to their visits the cam- 
panulate form of flower was evolved. Unbidden guests were. 
excluded from the honey in the first division by the development 
of deep honey-passages, cross-fertilisation in case of bees’ visits 
being insured by the position of the anthers in a ring close round 
the style (sub-genus Cwlanthe; species purpurea, pannonica, 
punctata, eruciata, asclepiadea, Pneumonanthe, Frelichu, frigida, 
acaulis). Later, as Lepidoptera made their influence felt, the corolla 
in Celanthe got longer and narrower, the folds which narrow it 
became more perfect, and the bilobed stigma became developed 
into a disk closing the mouth of the tube. Thus resulted the 
Alpine sub-genus Cyclostigma, adapted for long-tongued Lepidop- — 
tera (species bavarica, verna, estiva, umbricata, pumila, utriculosa, 
nivalis). 3 
In the second division, hairs on the corolla afforded imperfect 
protection against unbidden guests, and narrowing of the corolla 
made it more certain that both stigma and anthers should be 
touched by the bee (sub-genus Crossopetalum ,; species ciliata, L.). 
And finally, in a special offshoot of this division, as Lepidoptera here — 
also came to have a decided influence as cross-fertilisers, the fringe 
of hairs at the mouth of the corolla became more developed, 
excluding all visitors except humble-bees and Lepidoptera from the ~ 
honey, and the corolla became so narrow that Lepidoptera as well 
as humble-bees must perform cross-fertilisation in inserting their — 
proboscides (sub-genus Endotricha ; species campestris, germantca, 
Amarella, obtusifolia, tenella, nana). : 
The primitive yellow colour, retained in G. lutea, was gradually 
exchanged for blue by the influence of the humble-bees, and 
instructive transition-stages in this process are preserved among” 
the species of Celanthe.1 But after the blue colour was once | 
firmly established it was retained throughout the changes by whichy 
Celanthe passed into Cyclostigma (609). ; 
' CO. pwnetata has only blue spots on the pale-yellow ground of the corolla ; and in ‘ 
C. purpwrea, the outside of the corolla is bluish-purple, but the inside is still yellow. 
