Multiplication of Extremes 751 



Of course the application is limited, and forage- 

 crops and the greater number of vegetables will 

 always necessarily be propagated by seed. 



Nature ordinarily prefers the sexual way. 

 Asexual multiplications, although very common 

 with perennial plants, appear not to offer im- 

 portant material for selection. Hence it fol- 

 lows that in comparing the work of nature 

 with that of man, the results of selection fol- 

 lowed by vegetative propagation should always 

 be carefully excluded. Our large bulb-flowers 

 and delicious fruits have nothing in common 

 with natural products, and do not yield a stand- 

 ard by which to judge nature's work. 



It is very difficult for a botanist to give a sur- 

 vey of what practice has attained by the asexual 

 multiplication of extremes. Nearly all of the 

 large and more palatable fruits are due to such 

 efforts. Some flowers and garden-plants af- 

 ford further instances. By far the greatest 

 majority of improved asexual varieties, how- 

 ever, are not the result of pure intra-specific 

 selection. They are due largely to the choice 

 of the best existing elementary species, and to 

 some extent to crosses between them, or be- 

 tween distinct systematic species. In practice 

 selection and hybridization go hand in hand and 

 it is often difficult to ascertain what part of 



