208 Experimental Zoology 



tion the particular wild forms found in his vicinity. More often, 

 however, the results may be due to the wild forms having been 

 crossed with the domesticated forms so that the characters of 

 the former have become impressed on the domesticated animals 

 and plants. 



There is satisfactory evidence in the case of plants to show that 

 wild "varieties" and elementary species have often been crossed 

 with domesticated plants in order to produce hybrids having one 

 or more of the characters of the wild forms. Not only have wild 

 varieties of the surrounding country been used, but wild varieties 

 from all parts of the world, especially in modern times. Thus 

 many of our domesticated animals and plants are hybrids, and 

 the process of selection has been employed to pick out, amongst 

 the great diversity of types produced in this way, those forms 

 that have a practical value or that appeal to man.'s aesthetic or 

 commercial taste, or to his fancy for novelties. 



It is probable in many of these cases that the wild " varieties " 

 that have yielded valuable results are true elementary species 

 having fixed characters that have come from germinal variation, 

 and not local races whose peculiarities are due solely to the exter- 

 nal conditions to which they have been subjected. 



Selection under Domestication of Mutations, Saltations, Sports, 

 and Discontinuous Varieties in General 



It is probable that the sudden occurrence of sports or saltations 

 has furnished breeders with much of the material for the produc- 

 tion of new forms. It has long been known that new types ap- 

 pear in domesticated animals and plants. If these are picked 

 out selected and progeny raised from them, it is possible 

 to establish a new race. In the case of hermaphroditic plants, 

 self-fertilization of the new individual will give at once a large 

 number of individuals like the parent. In unisexual animals 

 and plants the new form must be crossed with the original 

 stock from which it sprang. In some cases all of the offspring 

 may be like the new form, and from some of them a new, fixed 

 type may be raised. In other cases, all the offspring may be 



