154 THE GARDEN OF EARTH 



will bring some here instead; a very fair and wise 

 exchange. 



The Butterfly Orchis grows its pollen in two tiny 

 lumps, close together. When a butterfly enters to feast 

 on the sweet nectar, it oftens happens to press its forehead 

 against these little lumps, which, being very sticky, 

 remain attached like a new-fangled head-dress. But 

 the visitor does not keep this burden long. Going into 

 other flowers, it is pretty sure to press soon against a 

 pistil-tip, leaving there part at least of the head-dress. 



In all such Cross-Fertilisation work, done by winds 

 and insects, as in the " Crossing " work of gardeners, not 

 only is ordinary fertilisation carried on, but also the 

 growth of fresh varieties is advanced. 



Not that " Crossing " or " Cross-Fertilisation " will 

 always account for such fresh varieties. Differences do 

 appear from time to time, with no apparent reason; 

 differences in size, in shape, in the form and colouring of 

 flowers, in modes of growth. Plants are perpetually 

 producing slight variations in their offspring; and the 

 power to do so seems to be inborn. Fresh kinds, fresh 

 types, are from time to time found in them, suddenly 

 and unexpectedly. 



This brings us naturally to a recollection of Darwin's 

 favourite thought " The survival of the fittest," by 

 which he meant the survival of the strongest, of the 

 healthiest, of the best-fitted to make their way in life. 

 Such " survival " depends mainly on the plants' power 

 of response and of self-adaptation to surroundings. 

 A slight illustration of how this power works may be 

 offered here. 



