— 146 — 



engl. transl., page 62), whicli are the most important of all 

 known insects in the fertilization of flowers, never coilect pollen 

 without moistening it with nectar. 



In consequence of this, we mustassume that no poUen-flower 

 can be completely adapted to fertilization by long-tongued bees, 

 for those insects must visit other flowers in which they can find 

 nectar, as well as pollen-flowers. 



Therefore, when the ancestors of Commelyna had reached the 

 stage Tinnantia, it was of great advantage to them that there 

 should be developed, in the connectives of their upper stamens, a 

 juice apt to take the place of honey, and to be used by the 

 visitors to moisten the pollen. 



As soon as the flowers began to vary in this direction, i. e. as 

 soon as the connectives w' began to contain a juice, this sub- 

 stan ce became gradually more abundant by natural selection. 

 At the same time the connectives of ?n* increased in size(l), and 

 they became conspicuous enough to allow the yellow hairs to 

 disappear. The production of pollen in the anthers m* became 

 gradually more reduced, but the stamen m', which lay under 

 the style, became at the same time curved upwards. lts anther 

 became larger, the production of pollen in it increased, and by 

 this processthe supply of pollen was restoredin the flower. 



The mode of dehiscence of m' lias been modiüed so, that the 



pollen has been emitted at the anterior (dorsal) side (flg. 14) : 



this has made the anther m' look conspicuous, and the stadium 



Commelyna was reached. 

 In Comm. tuOerosa, spontaneous self-fertilization is excluded 



as long as the flower is open, because uo pollen can fall upon 



the stigma (flg. 1). When the flower is crumpled (about I P. M.) 



the stigma comes perhaps into contact with some of the anthers, 



or with a petal upon which some pollen may have fallen when 



the flower was open. 



Commelyna Karaiüinskii (flg. 3, 4, 5) has the same structure 



as C. tuberosa, but all the organs of the flower are larger than 



(1) This evolution is illustrated by the ontogeny of the anthers m*; 

 see fig. 9-13. 



