606 IMPROVEMENT OF LIVING THINGS BY MAN 



On abandoned farms the plants soon tend to revert or go back to 

 wild conditions. And if we are to produce better plants and 

 animals, we must continually select the best products for breeding 

 as well as give them the best possible environment. 



Heredity is a much more complicated process than we once 

 thought. Laws of heredity discovered by Gregor Mendel and 

 worked out more recently by a number of scientists have shown 

 that the breeder may be able to get much more exact results than 

 was thought possible a few years ago. 



There has been a good deal of discussion among people lately 

 as to the comparative importance of environment and heredity 



in the lives of people. 

 The philanthropist says, 

 " Give me an opportunity 

 to improve the conditions 

 of the slum dwellers and 

 I will make happy and 

 healthy individuals out of 

 them." And the breeder 

 of plants or animals says, 

 " I cannot improve my 

 plants or animals unless I 

 give them proper condi- 

 tions of food and water 

 and air in their surround- 

 ings. But even if I give 

 them the best of these 

 conditions, I cannot make 

 a poor animal or plant of 

 poor stock into one having 

 good qualities." 



We have learned from 

 observation that environ- 

 ment does play a very big 

 part in the lives of plants 

 and animals. Not only will a plant or animal die if it is deprived 

 of any one environmental factor, but frequently it will be con- 



Clarke 



A white birch tree growing on a rock sent long 

 roots over the sides of the rock to the soil lying be- 

 side it. How has the environment changed the 

 tree? 



