620 Mutations 



dental transference of new qualities into the 

 already existing varieties by cross-pollination 

 through the agency of insects. Instead of giv- 

 ing long lists of these novelties, I may cite the 

 black tulipSj which cost during the first few 

 years of their introduction about $25.00 apiece. 



Horticultural mutations are as a rule very 

 rare, especially in genera or species which have 

 not yet been brought to a high degree of varia- 

 bility. In these the wide range of varieties and 

 the large scale in which they are multiplied of 

 course give a greater chance for new varieties. 

 But then the possibilities of crossing are like- 

 wise much larger, and apparent changes due to 

 this cause may easily be taken for original mu- 

 tations. 



The rarity of the mutations is often proved 

 by the lapse of time between the introduction 

 of a species and its first sport. Some instances 

 may be given. They afford a proof of the length 

 of the period during which the species remained 

 unaltered, although some of these alterations 

 may be due to a cross with an allied form. 

 Erythrina Crista-galli was introduced about 

 1770, and produced its first sport in 1884, after 

 more than a century of cultivation. Begonia 

 semperflorens has been cultivated since 1829, 

 and for half a century before it commenced 

 sporting. The same length of time has elapsed 



