70 BOTANY 



mate most closely to the type they desire. After 

 many generations of such breeding, forms have been 

 obtained which differ materially from either of the 

 original parents. The most notable gardener at the 

 present time who has undertaken this work on a large 

 scale and has obtained many useful or beautiful varieties, 

 is Luther Burbank, who has extensive experimental 

 gardens in California, and whose varieties of fruit are 

 grown all over the world. 



But though it is the most practically useful branch 

 of the subject, the mere production of economic varieties 

 is by no means the most interesting branch of the study 

 of breeding in plants. The gardeners' results, as a rule, 

 have been obtained by more or less haphazard crossing, 

 and from them alone there are few indications of the 

 great laws that underlie the production of the new 

 forms and their bearing on evolution and heredity. 



The great work of Charles Darwin, who established 

 the theories of evolution and the flux of species on in- 

 numerable minute observations, is so universally recog- 

 nised, and has had so many more or less popular 

 exponents, that there is no need to enlarge on " Dar- 

 winism " in these pages. 



All the problems of heredity and the means of trans- 

 mission of characters are of supreme importance to 

 the evolution theory, and, since Darv/in, the next 

 most important contribution to the knowledge of 

 heredity was made by the Austrian monk, Mendel. 

 He found that an extremely simple numerical law 

 governed the appearance of the different characters in 

 the second generation of the results of cross-breeding, 

 and that, if we note any one given pair of characters, 

 they appear in the second generation in the proportion 

 of one of one kind, one of the other, and two of the 

 mixed character. This can be expressed in algebraic 



