THE SCENTED CALLA 



The development of the scented calla, then, 

 through artificial selection based on the recog- 

 nition of the value of fragrance as an addition 

 to the attractiveness of this flower, represents 

 in a small way and in epitome the history of 

 the developnaent of numberless races in nature 

 through the operation of natural selection. 



In this particular case, natural selection prob- 

 ably would not have resulted in the production 

 of a race of scented callas, because, as already 

 pointed out, fragrance of this character has no 

 value for this particular flower. It might even 

 chance that the fragrance which to our senses 

 is exquisite would prove unattractive or even 

 repellent to the flies that normally frequent the 

 spathe of the calla and aid it in perpetuating its 

 species. 



In that case natural selection would certainly 

 ensure the early destruction of the race of scented 

 callas. It may well have been through such 

 discriminative selection on the part of insects that 

 the calla lost its scent in the past ages. For of 

 course natural selection can operate quite as 

 effectively in weeding out organisms that have 

 undesirable traits as in perpetuating organisms 

 that show favorable variations. 



One process is necessarily complementary to 

 the other; they are two sides of the same shield. 



[83] 



