THE FRAGRANT CALLA 19 



The presentation of this subject puts us in 

 touch with one of the newest and doubtless one 

 of the most important aspects of the problem of, 

 evolution. 



Since Darwin we have fully understood that 

 all evolution of organic forms must have its ori- 

 gin in variations. No two individuals even of the 

 same species are precisely alike, and it is not at all 

 unusual to find individuals of a species showing 

 very considerable differences, even as regards the 

 essentials of size and form and function. Indeed, 

 a certain range of such variations is considered 

 to be absolutely normal. 



One would never state, for example, that any 

 particular bird has a wing or beak or tail of 

 precisely a given length; instead of this the 

 ornithologist records the average or mean length, 

 or the limits of variation shown by different 

 specimens. 



And it is universally recognized, since Darwin 

 gave us the clue, that the building up of new 

 species must be brought about through the selec- 

 tion of favorable variations. A bird with an extra 

 long wing, for example, might be able to fly a 

 little faster and secure its insect prey with greater 

 facility than its fellows ; and this slight advantage 

 might be instrumental in saving the life of such a 

 bird, and thus enable it to transmit its peculiarity 



