896 HYBRIDIZATION-. 



ering them entirely worthless. Upon mvestigation, 

 it was discovered to have resulted from having ob- 

 tained seed from unhealthy trees, while seed from 

 the Swiss forests had produced trees which were in 

 perfect health. 



Hyhridization. From 1780 to 1790, Kolreuter 

 published the results of his experiments in hybri- 

 dizing vegetables. According to Mr. Herbert, this 

 interesting branch of horticulture commenced with 

 this celebrated man ; but that his efforts were com- 

 paratively unnoticed, and induced no further eiForts 

 until those of Sir Thomas A. Knight, in England. 

 Mr. Herbert commenced his experiments upon veg- 

 etables in 1819. AVhile Mr. Knight considered 

 a fertile hybrid as proof positive that the parents 

 were of the same species, Mr. Herbert denied 

 it, and extended it to the genus, and thought there 

 was no difference between species and " permanent 

 or descendable varieties." This will be denied, 

 probably, by most modern physiologists. While va- 

 rieties change according to physical influences, spe- 

 cific characters do not. No two species ever became 

 so confused that there could not be drawn between 

 them a distinct line, although this specific character 

 may be varied in degree by these influences. One 

 of the most remarkable proofs of the fallacy of the 

 hypothesis which would make physical influences 

 produce mutability of species, is found in the fact 



