Chap. IX GRADATION OP ORGANS. 2G1 



lying quite loose. Tliese'grains, from their embedded 

 position, could never by any possibility have been le^ 

 on the stigma of a flower, and were absolutely useless. 

 Those who can persuade themselves that purposeless 

 organs have been specially created, will think little of 

 this fact. Those on the contrary, who believe in the 

 slow modification of organic beings, will feel no 

 surprise that the changes have not always been per- 

 fectly effected, — that, during and after the many 

 inherited stages of the abortion of the lower pollen- 

 grains and of the cohesion of the elastic threads, 

 there should still exist a tendency to the production 

 of a few grains where they were originally developed ; 

 and that these should consequently be left entangled 

 within the now united threads of the caudicle. They 

 will look at the little clouds formed by the loose 

 pollen-grains within the caudicles of Orchis pyramidalis, 

 as good evidence that an early progenitor of this plant 

 had pollen-masses like those of Epipactis or Goodyera, 

 and that the grains slowly disappeared from the lower 

 parts, leaving the elastic threads naked and ready to 

 cohere into a true caudicle. 



As the caudicle plays an important part in the 

 fertilisation of the flower, it might have been deve- 

 loped from one in a nascent condition, such as we see 

 in Epipactis, to any required length merely by the 

 continued preservation of varying increments in its 

 length, each beneficial in relation to other changes in 

 the structure of the flower, and without any abortion 

 of the lower pollen-grains. But we may conclude 

 from the facts just given, that this has not been the 

 sole means, — ^that the caudicle owes much of its length 

 to such abortion. That in some cases it has subse- 

 ■quently been largely increased in length by natural 

 selection, is highly probable; for in Bonatea speciosa 



