THE COMMON BELT. GENTIAN 53 



fertilisation, special contrivances exist which tend 

 to make self-fertilisation impossible. A very simple 

 method is the arrangement whereby the male organs 

 ripen and shed their pollen before the stigmas 

 are matm-e. This happens in the case of the Bell 

 Gentian. A close examination of a flower such as 

 that seen on Plate IX., or, better still, a comparative 

 study of several flowers in different stages of develop- 

 ment, some quite young and hardly open, others fully 

 mature, will enable us to follow the details clearly. 



The Bell Gentian is fertilised by humble-bees. 

 A bee, visiting a young flower in search of the honey 

 secreted at the base of the ovary, has to push its way 

 through one of the spaces between the stalks of the 

 stamens. The anthers at this stage are quite ripe and 

 dehisce each by means of two long slits. They open 

 outwards — i.e., towards the corolla and away from the 

 ovary. In the young flower, the stigmas are not 

 mature, but the pollen is ripe ; and when a bee forces 

 its way between the anther stalks, it shakes a cloud 

 of pollen dust out of the anthers on to its own back. 

 Later, when the bee seeks another flower in a more 

 advanced condition, in which the pollen has all been 

 shed, but where the stigmas are mature, it deposits 

 some of the pollen on them, when it enters the 

 flower. If by any chance the pollen of a flower 

 should reach the stigma of the same flower, it is 

 usually ineff'ective, because the stigmatic surfaces are 

 not ripe. 



Kerner states, however, that self-fertilisation may 



