HEREDITY AND VARIATION 201 



differ so far from the average as to deserve the name of a 

 " sport." A certain race of men have, let us say, 5 feet and 

 8 inches for their average height. Of ten thousand men 

 of the race not very many have precisely that height, but 

 almost all are near it, varying only two or three inches 

 on one side or the other. A very few individuals of the 



BLACKBERRY FIELD. 



ten thousand, however, will probably be almost seven feet 

 high, and a very few others may be not much over four 

 feet. These extreme individuals are " sports." l 



150. The student should now be able to understand 

 somewhat better the work of the plant breeder. (1) The 

 breeder studies the variations in the offspring of a germ 

 plant, and tries to preserve and propagate the variations 

 that seem most useful for man, for instance, the most 

 productive stalk of corn in a field. (2) He takes advan- 



1 There is a like natural variation in other qualities. Among men, for in- 

 stance, there is a general average of mental ability. Most men vary only a 

 little from this average ; but in a million there will be a few natural geniuses 

 and a few natural idiots. Both these classes are " sports." 



