22 LUTHER BURBANK 



It has already been said that the appearance of 

 a fragrant calla constitutes such a change. But of 

 course the anomalies that are usually listed as 

 mutations are often of an even more noticeable 

 character. A classical illustration was given by 

 Darwin himself in the case of the Ancon ram, 

 which was born with legs only half the normal 

 length, and from the progeny of which was 

 developed a short-legged race of sheep. 



But the word mutation had not come into 

 vogue in Darwin's time, and the idea of evolution 

 through such marked departures from the normal 

 was subordinated in Darwin's interpretation of 

 the origin of species, or at least in that of his 

 immediate followers, to the idea of advance 

 through the preservation of slight variations. 



So when, just at the close of the nineteenth 

 century, Professor Hugo de Vries came forward 

 with his "mutation theory," it had all the force of 

 a new doctrine, and was even thought by some 

 enthusiasts though not by its originator to be 

 in conflict with the chief Darwinian doctrines. 



The observations that led Professor de Vries 

 to the development of this theory were made on a 

 familiar American plant that had found its way 

 to Europe and was growing in profusion by the 

 roadside near Amsterdam. The plant is known 

 as the evening primrose. 



