XXV.] SUMMARY. 417 



strawberries are a direct modification of the Chile 

 strawberry. The initial variation occurred when spe- 

 cies were thought to be more or less immutable, and, 

 lacking exact historical evidence of introduction from 

 a foreign country, hybridization was the most natural 

 explanation of the appearance of the strange type. 

 This modified type has driven from cultivation the 

 Virginian berries, which were earlier introduced into 

 gardens ; and the original type of the Chilian straw- 

 berry is little known, as it tends to quickly disappear 

 through variation when impressed into cultivation. 

 The strawberry is an instance of the evolution of a 

 type of plant, in less than fifty years, which is so 

 distinct from all others that three species have been 

 erected upon it, which was uniformly kept distinct 

 from other species by the botanists who had occa- 

 sion to know it best, and which appears to have 

 been rarely specifically associated with the species 

 from which it sprung. 



27 SUR. 



