148 Changing Plant and Animal ISIature 



prey, mild grazing animals, insects sucking nectar from 

 plants, starfish everting their stomachs and insinuating them 

 between the shells of the oyster, the whale catching food by 

 swallowing a couple of hogsheads of water and straining out 

 thousands of smaller beasts. Endless varieties of food- 

 getting organs and processes can be found in one class of 

 animals alone like the insects or birds. 



There must be fitness to get water and at the same time 

 protection against being drowned out. Every plant, in so far 

 as it is a food maker or contains within its body nutrient 

 materials, becomes exposed to attack. Every animal is ex- 

 posed to attack from larger or stronger animals as well as 

 from smaller and more subtle enemies. Protection through 

 toughened skin, through hairs and spines, through bark and 

 hide, through armors and shells, through stings and darts and 

 poisons, are found on every hand. 



The danger of excessive heat, the danger from drouth, 

 the danger of excessive cold, are met in myriad ways. Some 

 of the structures or arrangements that protect against 

 mechanical injury, such as hides, armors and furs, may serve 

 also to protect against excessive changes in temperature and 

 moisture. The feathers of the bird combine perfect in- 

 sulation against changes in temperature with extreme light- 

 ness. Desert plants show typically reduced leaf and stem 

 surfaces. Many plants and animals go into winter quarters 

 and some, by encasing themselves in cysts or capsules, lie 

 dormant until conditions for activity are more favorable. 

 The shedding of leaves in the fall may be looked upon as a 

 form of protection against the unfavorable conditions of 

 winter weather, since it reduces enormously the exposed 

 surface. 



Color in nature impresses itself upon the casual ob- 

 server primarily perhaps because of aesthetic interests. One 

 cannot go far afield, however, without discovering in color 

 suggestions of adaptive values to the individual plant or 

 animal. We have all been startled by the movement of a 

 frog or a bird that remained quite invisible, or at least in- 



