142 LUTHER BURBANK 



rias, suggest this close relation. Yet the fact that 

 they are indigenous to different continents shows 

 that they have been separated for a very long 

 period of time, although of common ancestry. 



The students of geological botany tell us that 

 there must have been a great mass of land in the 

 Southern Hemisphere at one time on which races 

 of plants developed and subsequently were iso- 

 lated on the land masses that are now known 

 respectively as South America, Africa, Austral- 

 asia and New Zealand. At that remote period 

 the Tigridias and Ferrarias were doubtless of one 

 stock, and the fact that their descendants of to- 

 day retain such elements of affinity as to puzzle 

 the botanists and to serve well the purposes of the 

 hybridizer gives another illustration of the won- 

 derful pertinacity with which the characteristics 

 of a plant are sometimes transmitted through 

 almost numberless generations without radical 

 transformation. 



It is little wonder that the earlier biologists, 

 before the coming of Darwin, when confronted 

 with such observed cases of affinity between races 

 that must have been separated for countless 

 thousands of years, were strong in their faith in 

 the fixity of species. 



Yet the facts of variation, even within a few 

 generations, are too obvious to escape attention. 



