Selection in Agriculture and Horticulture. 75 



In choosing cases for the scientific study of the pro- 

 cess of selection it is of the highest importance to ex- 

 ckide all those in which crossing has taken place, or where 

 it has not been excluded with absolute certainty. Many 

 genera and species owe their present range of forms 

 (which is what breeders call variability) almost entirely 

 to the repeated crossings between the original wild forms 

 that w^ere introduced, whether these were different Lin- 

 nean species or numerous elementary species of such. 



There are two chief categories to be distinguished. 

 First there are those genera in which a very wide range 

 of form is desired, and for this purpose almost every 

 conceivable cross between the different varieties has been 

 carried out. The best, either from the utilitarian or 

 from the decorative point of view, are then put on the 

 market and are, in the eyes of the layman, an inscrutable 

 medley. Fuchsias, dahlias, chrysanthemums, wheat and 

 potatoes are the best known examples. The novelties 

 of the breeders arise in these cases almost without ex- 

 ception by the deliberate combination of characters al- 

 ready existing in the old types. 



Secondly there are the genera which have developed 

 in a definite direction since the beginning of their culti- 

 vation, e. g., begonia, gladiolus, caladium, amaryllis, 

 canna and many others. The improvement in these 

 cases has almost always been the result of the discovery 

 of new wild species. These have been crossed with the 

 cultivated bastard race and in this way the desired char- 

 acters of the former have been transferred to the latter. 

 The large and beautiful blossoms, the caladiums with 

 variegated leaves, the hardy gladioli etc. have been got 

 in this way. The characters of the new varieties already 

 existed in nature, distributed between the different spe- 



