xiv MAKING NEW PLANTS 173 



potato, they " keep true," that is, do not change in 

 character. 



Most of our cultivated plants, except where the 

 seeds are the edible part, are reproduced by some 

 part of the parent plant, or, as the botanists say, 

 " vegetatively." This is a method which has 

 many advantages. Take the potato, for example. 

 It is possible, by the crossing and selection process 

 which we have described, to make a new variety of 

 potato, which will combine merits found hitherto 

 in separate kinds. That is to say, it may be hardy 

 like one parent, and very early or very prolific like 

 the other. Now, if this potato had to be grown 

 from seed each year, not only would the process be 

 much slower than the present way, where a piece 

 of potato is put into the ground, but also the seed- 

 lings would not be all alike. Some would have 

 kept their hardiness, but lost the power of ripening 

 early. Others would be ready early, but would be 

 delicate, and so on. 



This means that though man can make almost 

 any kind of plant he likes, if he has patience 

 enough, yet it is very difficult for him to give 

 his " creations " the power of lasting, the stability 

 which natural plants have. In Nature, plants are 

 generally very like their parents, they are generally 

 stable. By cultivation, and especially by crossing, 

 man can easily destroy this stability. He can, as 



