GENERAL RELATIONS IN INHERITANCE 311 



and these as it turns out are of a somewhat uniform pattern. 



But under domestication, or in the laboratory, conditions 

 can be fitted to the new types, even if they are inefficient, 

 even if they are weak or defective; they can be coddled and 

 their needs supplied. Thus many types survive and multiply 

 that in a state of nature would quickly disappear. In culti- 

 vated plants, for example, combinations that give individu- 

 als that are unusual in size, shapes and color, are of special 

 interest to the cultivator. They are therefore cultivated 

 with care in greenhouses or nurseries by the use of special 

 fertilizers and other favorable conditions. They are induced 

 to multiply, while the common types, which in themselves 

 may be best fitted for life, are rejected and destroyed. The 

 situation found in nature is thus reversed: the extraordinary 

 types are induced to multiply, the ordinary ones excluded. 

 It thus happens that in cultivated plants great numbers of 

 strange, striking and extreme varieties are produced, such 

 as do not occur in the same species in a state of nature. 

 The results appear in the extraordinary forms, sizes, colors, 

 seen in an exhibition of Dahlias, Chrysanthemums, Be- 

 gonias, or the like. 



In such plants usually the original varieties found in 

 nature are not very diverse or showy; the number of types 

 of form and color are few. These are crossed; thousands 

 of seedlings are produced. Most of these give plants not 

 very different from the parents. These are discarded. 

 Others, with unusual combinations of genes, give the large, 

 showy individuals of colors and shapes diverse from those 

 of the original varieties. These are induced to multiply by 

 bulbs, cuttings or other vegetative methods, until from the 

 single plant an entire variety Is produced. 



If individuals of these striking varieties are allowed to 

 cross and produce seeds, it is well known that they do not 

 "breed true." The unusual combination of genes that pro- 

 duced them is broken up by the processes of biparental 



