CiiAP. IX. CONCLUDING EEMAKKS. 293 



is completely sterile without such aid in another 

 district. 



Finally, if we consider how precious a substance 

 pollen is, and what care has been bestowed on 

 its elaboration and on the accessory parts in the 

 Orchidese, — considering how large an amount is 

 necessary for the impregnation of the almost innumer- 

 able seeds produced by these plants, — considering that 

 the anther stands close behind or above the stigma, 

 self-fertilisation would have been an incomparably 

 safer and easier process than the transportal of pollen 

 from flower to flower. Unless we bear in mind the 

 good effects which have been proved to follow in most 

 cases from cross-fertilisation, it is an astonishing fact 

 that the flowers of the Orchidese should not have been 

 regularly self-fertilised. It apparently demonstrates 

 that there must be something injurious in this latter 

 process, of which fact I have elsewhere given direct 

 proof. It is hardly an exaggeration to say that Nature 

 tells us, in the most emphatic manner, that she abhors 

 perpetual self-fertilisation. 



