86 HEREDITY AND VARIATION 



Variation leads ; the breeder follows. The breeder's method is to 

 notice a desirable novelty, and to work up a stock of it, picking 

 up other novelties in his course — for these genetic disturbances 

 often spread — and we may rest assured the method of nature is 

 not very different " (1905, p. 578). 



This is obviously a very important change of view, though 

 it is also in a way a return to what Darwin himself taught. 

 ' Variation leads ; the breeder follows." But more than that : 

 Variation leads by leaps and bounds. As Mr. Bateson says, let 

 the believer in the efficacy of selection operating on continuous 

 fluctuations try to breed a white or a black rat from a pure 

 strain of black-and-white rats by choosing for breeding the 

 whitest or the blackest ; or to raise a dwarf (" Cupid ") sweet 

 pea from a tall race by choosing the shortest. It will not work. 

 Variation leads and selection follows. 



Illustrations of Discontinuous Variation 



Wonder Horses. — The so-called wonder-horse " Linus I." 

 had a mane eighteen feet long and a tail twenty-one feet long. 

 The parents and grandparents had unusually long hair. This 

 seems a good illustration of a " sport " or discontinuous variation 

 which not only persisted for several generations, but increased 

 very rapidly. 



Shirley Poppies. — The well-known Shirley Poppies arose 

 from a single discontinuous variation, which may have occurred 

 often before Mr. Wilks saved it from elimination and made it 

 the ancestor of a prolific and distinctive stock. 



Star Primrose. — The graceful star primrose {Primula stellata) 

 arose as a sport from the conventional Chinese primrose, and 

 was raised by Messrs. Sutton into a favourite stock. It had 

 been thrown off before as a sporadic variety over and over 

 again, but was " promptly extirpated because repugnant to 

 mid-Victorian primness." 



