BEES IN RELATION TO FLOWERS. 253 



five stamens fully developed, while the stigma remains 

 quite out of their reach. Later, when all the pollen 

 is discharged from the anthers, the pistil throws 

 up its style and stigma, now ready for fertilisation, 

 which must be effected by the transfer of pollen from 

 some other blossom of the same or another plant 

 of the species. This transfer is effected, usually, by 

 the bees. 



Another example of this non-coincidence in the 

 times of development of the stamens and pistil is 

 found in the foxglove (Digitalis purpurea), but the 

 fertilisation is effected by the larger humble-bees. 

 The two upper and longer stamens shed their pollen 

 before the two lower and shorter ones. This 

 arrangement partly avoids the risk of self-fertilisa- 

 tion, while their position, which changes just when 

 the anthers are ripe, enables them to smear the 

 under side of any entering bee ; while they also shed 

 their pollen abundantly on the thickly-set hairs 

 lining the mouth of the corolla. A second use is 

 served by these hairs, viz., that of obstructing the 

 entrance of the smaller kinds of bees, which could not 

 so effectually fertilise the ovules. The larger sorts, 

 in their raids upon the nectar, carry pollen from 

 flower to flower, thus in the best manner bringing 

 about the most desirable result of cross-breeding. 



Passing now to plants in which the pistil develops 

 earlier than the stamens, we may note the knotted 

 figwort {Scrophularia nodosa). On making a section 

 of a recently opened flower, the style, with its stigma, 

 may be observed protruding just beyond the lip of 

 the corolla, while the stamens are hiding away, as it 

 were, in a little pouch below the entrance of the 



