248 IMPROVEMENT OF PLANTS AND ANIMALS 



variety may have a different useful character ; and 

 by a crossing of the two varieties a new variety may be 

 obtained that will possess the two useful characters 

 of both parent varieties. Crossbreeding either of 

 plants or of animals always produces variations, but 

 these variations may be of no value. If there is to be 

 a gain in crossbreeding, the new variation must be an 

 improvement, and must become a hereditary char- 

 acter in the new variety. 



QUESTIONS 



1. What is the law of heredity ? 



2. How does the farmer use the law of heredity to improve 

 plants and animals ? 



3. What is the law of variation? 



4. What effect has environment upon qualities of plants and 

 animals? Give examples. 



5. What is crossbreeding ? j 



REFERENCES 



Write to your Agricultural College for bulletins on animal 

 breeding and plant breeding. 



