BETTER PLANTS AND ANIMALS 13 



concealed among many others. The continued selection simply 

 amounted to a weeding-out process, whereby the better race was 

 gradually made more nearly pure and freed from its poorer 

 associates. 



14. The ear-row method better than mass selection. By the 

 method formerly general in both Europe and America, and still 

 practiced to some extent, a considerable number of heads from 

 an ordinary field are selected and weighed, and the heaviest 

 saved for planting. The next year selection from the field is 

 made in the same way, and so on indefinitely. There is no 

 question but that a continuous advance is made by this method, 

 but progress is slow because it is not possible to weed out all 

 the poorer individuals and save only the best for seed. A field 

 of wheat, for example, consists of millions of individuals, each 

 with its own characteristics, powers, and capabilities. 



A field of wheat may be compared to a great city. Some of 

 the inhabitants come from sound families, others from those 

 which are unsound. If men were to be selected from New 

 York City for an Arctic expedition to last three years, in addi- 

 tion to requiring of applicants conformity to certain physical 

 standards, the family histories of the applicants would be ex- 

 amined for probable latent defects. Selection would be rigid. 

 Or suppose one man were desired out of that great city's popu- 

 lation to act as a secret-service bodyguard to the president of 

 the United States. It is likely that the family histories of the 

 applicants would be even more rigidly and thoroughly examined, 

 since selection is limited to choosing one individual. 



A field of wheat may be thought of as a city of wheat plants, 

 all slightly different from one another. It is plain that if we 

 select one hundred of the best-appearing, or heaviest, or largest 

 heads, we shall probably get as offspring from them many wheat 

 plants that average better than the general population. If we 

 go a step farther, we may find a way of selecting the best wheat 

 plant in the field. In the case of the supposed bodyguard selected 

 from several millions of a large city population, we should both 

 test the man and study his family. In the case of wheat we test 



