294 Plant Life and Evolution 



the common domestic plants have been very much 

 changed in the course of the centuries during which 

 they have been cultivated. It is highly probable 

 that the earliest agriculturalists took advantage of 

 the variations which occur in wild plants, and that 

 this process, in time, resulted in the widely different 

 varieties which have replaced the primitive stocks, 

 which in many cases we can no longer with cer- 

 tainty recognize. Hybridization has also undoubt- 

 edly played an important part in the origin of many 

 cultivated races of plants, but it is not likely that 

 this was consciously practised in early times, al- 

 though it is not improbable that hybrids may have 

 been responsible for some of the early cultivated 

 plants. 



Plant Breeding. Of late years, however, the de- 

 velopment of new forms of plants has been the de- 

 liberate aim of a host of experimenters, and hun- 

 dreds or even thousands of well-marked varieties, 

 often much more different in appearance from each 

 other than are many natural species, have resulted 

 from their labors. One has but to consider the enor- 

 mous number of new varieties of almost any popular 

 flower or fruit apples, grapes, roses, narcissi, 

 etc., which the catalogues advertise every year, to 

 realize the part which man has deliberately played as 

 a creator of new forms of plants. These may be the 

 result of spontaneous variation and subsequent se- 

 lection, or by skilful crossing of different species or 

 varieties, the tendency to variation may be very 



