Ecologic Study of Living Organisms 639 



wild types directly and indirectly. Many wild types are destroyed as 

 weeds because they interfere with the normal development of domestic 

 types. Many wild types influence the development of domestic types; 

 an example is the destruction of corn plants by the European corn borer 

 which may spend part of its life cycle in a great variety of weeds and 

 other types of plants. Hence, the number of wild types which sur- 

 round a field of corn and which harbor corn borers affects the domestic 

 corn plants. The relationship between the barberry bushes and the rust 

 of wheat is another example. A great variety of new types ot plants 

 have been "artificially" produced because they possess certain qualities 

 which are beneficial for foods, shelter, fuel, or industry. The production 

 and cultivation of many of these new species naturally affect the ecology 

 of other plants in their vicinity. 



(d) Destruction of Detrimental Animals and Plants by Man: This 

 type of destruction not only affects the animals and plants being de- 

 stroyed, but their absence affects many others indirectly by giving them 

 more food, light, space, and moisture. The destruction of one kind of 

 plant may cause animals which were dependent upon it to turn to some 

 other type of plant and thus affect it. The destruction of certain plants 

 may expose others to sunlight, heat, winds, etc., to which they were 

 not accustomed. This will present a new ecologic factor for the re- 

 maining plants. 



II. TYPICAL ENVIRONMENTS AND THEIR FAUNA 

 AND FLORA 



The following summary of a few typical environments and the types 

 of organisms usually found in such environments will illustrate many 

 points in the study of ecology. Environments for convenience will be 

 divided as follows: 



A. Water or aquatic 



1. Rapid streams 



2. Pools 



3. Ponds 



4. Lakes 



B. Land or terrestrial 



1. Open fields 



2. Deserts 



3. Tundras 



4. Forests 



