176 TILLEKS OF THE GEOUND CHAP. 



made out of a pumpkin, and changed back into a 

 pumpkin as soon as the clock struck twelve. Well, 

 our apples and pears, all our garden fruits and 

 flowers and vegetables, indeed, were made out of 

 poor, useless, wild plants, arid the moment we 

 cease to try to keep on improving them, they will 

 begin to slip back into their original state. The 

 change is not so sudden as in the fairy tales, but it 

 is just as real. 



One other point about improving cultivated 

 plants is important. We have just seen that in 

 the case of plants produced from seed, there is 

 always the risk that the seedlings will not have 

 all the good qualities of their parents, a risk which 

 does not exist when the plants are reproduced 

 vegetatively. But plants which are always repro- 

 duced from seeds are at least frequently annuals, 

 and they have the great advantage of quick growth. 

 There are some grains which can be sown and 

 harvested within a period of three months. In 

 warm countries, if there is enough water, more than 

 one crop of these plants can be raised in the year. 

 The result of this is that improvements can be made 

 rapidly. 



On the other hand, when plants are not 

 annuals, they very frequently take several years, 

 sometimes many years, to come to flowering age, 

 and in that case improvement by crossing must be 



