How Domestic Varieties Originate 215 



breed animals. The fact is, however, that such exactness 

 will never be possible, because plants are very unlike 

 animals in organization, and because, also, the objects 

 sought in the two 

 cases are character- 

 istically unlike. 

 Plants, as we have 

 seen, are made up 

 of a colony of poten- 

 tial individuals, and 

 to breed between 

 two plants by cross- 

 ing means that we 

 must choose the 

 sex-parents from 

 amongst as many 

 individuals as there 

 are f 1 o wers or 

 branches on the two 

 plants, whilst in 

 animals we choose 

 two definite personal 

 parents. And these 

 personal parents are 

 either male or fe- 



FIG. 51. Improving the tomato : A, fruit of 

 approximately ideal form secured by cross- 

 ing and selection; B, fruit showing im- 

 perfections and undesirable characters. 

 (Yearbook, U. S. Dept. Agric.) 



male, and the union 

 is essential to the 

 production of offspring, whilst in plants each parent 

 that is, each flower is usually both male and female^ 

 and the union of two is not essential to the produc- 

 tion of offspring, for the plant is capable of multiplying 



