594 THE FERTILISATION OF FLOWERS. [PART Ly, 
selective agent. Different groups of insects, according to their 
sense of taste or colour, the length of their tongues, their way 
of movement and their dexterity, have produced various odours, 
colours, and forms of flowers; and insects and flowers have 
progressed together towards perfection. 
The transition from wind-fertilisation to insect-fertilisation and 
the first traces of adaptation to insects, could only be due to 
the influence of quite short-lipped insects with feebly developed 
colour-sense. The most primitive flowers are therefore for the 
most part (except, for instance, Salix) simple, widely open, regular, 
devoid of honey or with their honey unconcealed and easily 
accessible, and white or yellow in colour (e.g. most Umbellifere and 
Alsinee, many Ranunculacece and Rosacec. 
The carrion-loving Flies were from the first marked out by 
their peculiar tastes to produce certain peculiar flowers. Preferring 
those colours and odours which guided them to their primitive 
food, they produced, wherever they got special influence, dull, 
yellowish, or dark-purple colours, often accompanied with a putrid 
smell. The stupidity of flies also favoured the production of cer- 
tain contrivances to insure crossing, ¢.g. the prison-flowers of Arwim 
and Aristolochia, the traps of Pinguicula alpina, Cynanchum, and 
Stapelia, or the deceptions of Paris, Ophrys, and Parnassia. 
Gradually, from the miscellaneous lot of flower-visiting insects, 
all much alike in their tastes, there arose others more skilful and 
intelligent, with longer tongues and acuter colour-sense ; and they 
gradually caused the production of flowers with more varied 
colours, honey invisible to or beyond the reach of the less intel- 
ligent short-tongued guests, and various contrivances for lodging, 
protecting, and pointing out the honey. 
Lepidoptera, by the thinness, sometimes (Sphingide) by the 
length of their tongues, were able to produce special modifications. 
Through their agency were developed flowers with long and narrow 
tubes, whose colours and time of opening were in relation to the 
tastes and habits of their visitors. We may thus distinguish flowers 
adapted for butterflies (Dianthus deltoides and many Silenee), or for 
moths (Platanthera) ; for diurnal hawk-moths (Gentiana bavarica, 
G, verna), for nocturnal hawk-moths (Lonicera Caprifolium) ; and 
intermediate stages (e.g., Crocus vernus). The acute sense of smell 
in Lepidoptera reveals itself in the aromatic scent of Pinks, 
Nigritella, Daphne striata, ete., and the colour-sense of butterflies 
is shown in the flowers, usually red and prettily marked, which 
are due to them. 
