200 



MAKING BETTER PLANTS 



race. A six-fingered child is a "sport." So is a giant or 

 a dwarf. 1 The higher and more complex the kind of life, 

 the more likely it is, apparently, to produce " sports " in its 

 offspring. 



147. Heredity. A "sport" gives us a shock of surprise 

 at first, because we expect offspring to resemble the parent 

 closely. The only reason that most of us have for expect- 

 ing this likeness is that offspring usually do resemble the 

 parent. When we wish to speak of the force in nature 

 that causes the offspring to tend to repeat the character 

 of the parent, we call it heredity. 



148. Variation. But happily in all natural organisms 

 there is not only this force of heredity, or a tendency to 



repeat the parent, but 

 also an opposite tendency 

 which we speak of as 

 " the tendency to varia- 

 tion." If it were not 

 for this second force, 

 neither nature nor man 

 could much improve 

 either plants or animals. 

 149. These two great 

 forces, heredity and varia- 

 tion, work together in all 

 living organisms. He- 

 redity secures a general 

 likeness in each variety, 

 but there is always some 

 variation. In a corn- 

 field, even if all the seed came from one plant, the stalks 

 differ from one another, and some differ a good deal 

 from the average. Once in a long while, one stalk may 



1 Unless the dwarfing has been caused by treatment after birth. 



IMPROVED BLACKBERRY. 



