

•TANY OF THE LIVING PLANT 



small and inconspicuous. Where animal agency is used, the flowers 

 arc attractive and conspicuous by their scent, by honey-secretion, 

 and by widely expanded floral envelopes of bright colour. The latter 

 attract the eye, the former the other senses of the animal, for instance 

 a bee, and lead her to visit the flower for her own purposes of gathering 

 honey or pollen. Incidentally the floral mechanism is so arranged, 

 in size and form of the parts, that pollen, often of a sticky nature, is 

 deposited on her body as she visits the flower. The flower may be so 

 formed as to lead her, for sake of convenience, to take a definite 

 position : consequently the pollen is deposited on a definite part of 

 her body (Fig. 220). The result of repeated visits to a succession of 



Pollination of Salvia pratensis. i, Flower visited by Humble Bee, showing the 

 projection of the curved connective from the helmet-shaped upper lip, and the deposit 

 of the pollen on the back of the Bee. 2, Older flower, with»connective withdrawn 

 and elongated style. 4, the staminal apparatus at rest, with connective enclosed 

 within the upper lip. 3, the same when disturbed by the entrance of the proboscis 

 of the Bee in the direction of the arrow. /=filament. c = connective. s = the 

 obstructing half of the anther, which produces no pollen. (After Strasburger.) 



flowers of like construction will then be that, if the stigmas correspond 

 in position to the spots on which she bears the pollen, they may 

 probably receive some part of it. Thus unwittingly she will have been 

 the agent of transfer of the pollen from the pollen-sac to the receptive 

 stigma. 



Such mechanisms have been elaborated in the course of Descent in 

 an infinite variety of detail. This is the biological meaning of the 



tractive features which flowers have assumed. It may even be seen 

 how certain floral types have been adjusted in relation to the visits 

 of certain animals, and show development parallel with them. A 

 good instance is that of the Aconite and the Humble Bee, to whose 

 visits the Aconite flower offers convenient access. A study of their 

 distribution across Europe and Asia shows that the northern limit 

 of occurrence of the two organisms almost exactly coincides. This 

 suggests the importance of the Humble Bee in the transfer of the 



