272 CREATION BY LAW. 



by which this is effected, and the Duke of Argyll ad- 

 mits the accuracy of his observations. In our British 

 species, such as Orchis pyramidalis, it is not necessary 

 that there should be any exact adjustment between 

 the length of the nectary and that of the proboscis of 

 the insect ; and thus a number of insects of various 

 sizes are found to carry away the pollinia and aid in 

 the fertilization. In the Angracum sesquipedale, how- 

 ever, it is necessary that the proboscis should be forced 

 into a particular part of the flower, and this would 

 only be done by a large moth burying its proboscis 

 to the very base, and straining to drain the nectar 

 from the bottom of the long tube, in which it occupies 

 a depth of one or two inches only. Now let us start 

 from the time when the nectary was only half its 

 present length or about six inches, and was chiefly 

 fertilized by a species of moth which appeared at the 

 time of the plant's flowering, and whose proboscis was 

 of the same length. Among the millions of flowers 

 of the Angra3cum produced every year, some would 

 always be shorter than the average, some longer. The 

 former, owing to the structure of the flower, would 

 not get fertilized, because the moths could get all the 

 nectar without forcing their trunks down to the very 

 base. The latter would be well fertilized, and the 

 longest would on the average be the best fertilized of 

 all. By this process alone the average length of the 

 nectary would annually increase, because, the short-nec- 

 taried flowers being sterile and the long ones having 

 abundant offspring, exactly the same effect would be 



