298 LIVES OF PLANTS AND ANIMALS 



salt water; in a fresh-water lake. What adaptations would the plants and 

 animals in the above list show? (Read Jordan and Kellogg, Animal Life, or 

 Kinsey's Introduction to Biology.) 



Self-Testing Exercise 



(1) (2) are affected by the factors of the 



(3), such as (4), (5), (6), and (7). 



Plants living in water have (8) tissues which hold (9) 



and are apt to have (10) leaves and (11) roots. 



Animals living in water show (12) for such life. The 



(13) of the water is of much importance to the (14) or 



(15) living in it. At great depths it is very (16). Lack of 



water results in adaptations in plants for (17) (18) 



such as (19) or (20) or (21) stems. 



Desert animals can get along without much water, but they 



(22) in the ground or keep in the (23) much of the time. 



Temperature is a very important (24) in determining not 



only the (25) and (26) found in a given (27) 



but also how they will (28). Animals and plants 



(29) (30) in hot areas, as witness the changing of garden 



(31) into (32) in southern California. Many fish, 



as trout or salmon, are only found in (33) water. Some 



animals can only live in water containing certain (34). 



Plants and animals may be influenced not only by the (35) 



but also by the (36) of light. 



PROBLEM VI. WHY DO PLANTS AND ANIMALS FORM 

 COMMUNITIES? 



Societies. All of the factors referred to act upon the plants we 

 find living together in a forest, a sunny meadow, along a roadside, 

 or at the edge of a pond. Any one familiar with the country 

 knows that we find certain plants, and only those plants, living 

 together under certain conditions, and, in a similar way, only 

 certain animals will be found to be associated together. 



Plants and animals associated under similar conditions, as those 

 of a forest, meadow, or swamp, are said to make up an association 

 or community. If we investigate such an association, we find it 

 to be made up of certain dominant species of plants ; that here and 



