392 PLANT AND ANIMAL BREEDING 



there were in 1925 nearly 19,000,000 horses, nearly 67,000,000 

 cattle, over 40,000,000 sheep, and about 65,000,000 swine in this 

 country, representing a money value of over $4,000,000,000, we 

 see how very important a part the domestic animals play in our 

 lives. 



Present Problems in Animal Breeding. — In spite of the fact 

 that this vast amount of money is represented by our domesticated 

 animals, it could and should be much more. Crosses in fowls 

 have been obtained that produce as many as 300 eggs from one 

 hen in a year; yet the average hen lays less than 100 per year. 

 A few cows of superior breeding in some of the state experiment 

 stations produce as much as 1000 pounds of butter fat each in a 

 year ; but the average cow produces little more than 200 pounds a 

 year. A bulletin of the Department of Agriculture says, " Good 

 judges believe that in the entire country one fourth of the cows 

 kept for their milk do not pay for their cost of keeping, and nearly 

 a fourth more fail to yield annual profit." This means that many 

 farmers do not know what their cows are producing. It means that 

 many farmers are poor, through either carelessness or ignorance. 

 The scientific breeding of milk cows would mean millions of dollars 

 in the pockets of the farmer, and an increase in that much-needed 

 commodity, milk, for our children. This is only one of the many 

 problems of conservation that will eventually be solved by our 

 animal breeders. 



Summary. — Variation and heredity are always at work in 

 living things. Man has made use of these tendencies for ages, 

 once blindly, but now with some knowledge. Since the discovery 

 of Mendel that unit characters are handed down by heredity, and 

 that the inheritance of these characters can be determined exactly, 

 our problems of plant and animal breeding have been made much 

 more exact. Selection of strong animals and plants is necessary, 

 conditions of culture must be carefully controlled, but the determi- 

 nation and isolation of beneficial unit characters is the big problem 

 for the future. 



Problem Questions 



1, What is heredity? How is it believed to be brought about ? 



2. What is variation? What two kinds of variations are there? Arej 

 they of eaual value in breeding? 



