MULTIPLICATION. 89 



most part their stamens and pistils in the same flower 

 (hops are an exception), and therefore they may be de- 

 scribed as structurally hermaphrodite. It does not, how- 

 ever, follow that they are functionally hermaphrodite 

 that is, that the pollen-grain of any particular flower ferti- 

 lises the germ-cell of the same flower. As a matter of fact, 

 the reverse usually happens, and the pollen of one flower 

 exerts its influence, not upon the germ of its own flower, 

 but upon that of another, perhaps situated on some other 

 plant. Cross-fertilisation is often necessitated by the cir- 

 cumstance that while the pollen of any particular flower may 

 be ripe, the stigma and the germ-cell of the same flowei 

 may not be ripe at the same time, or vice versa, and in 

 such case the co-operation of some other flower is needed. 



Transport of Pollen. It becomes, therefore, needful 

 to ascertain in what manner the pollen is carried from one 

 flower to another. This is effected in various ways some- 

 times the mere splitting of the anther with some degree of 

 force suffices to scatter the pollen, at other times the cur- 

 rents of air suffice to waft it from one flower to another, 

 while at other times insects of various kinds convey the 

 pollen from one flower and deposit it on the stigma of 

 another. 



The adaptations of floral structure to insect-agency in fer- 

 tilisation, as also the contrivances for excluding undesirable 

 visitors, are most varied and most remarkable, but they can 

 only be mentioned here. As a rule, it may be stated that 

 flowers endowed with bright colours, irregular construction 

 (like that of the pea or bean), or rich perfume are fertilised 

 by insect agency. The insects are attracted by the bright 

 colours, the perfumes, and the sweet secretions of the flower. 



