38 FORESTS AND MANKIND 



more difficult a need arose for more specialized structures 

 more complex machinery for existence. 



So all the trend of nature seems to be from simple structures 

 to complex. The earliest plant of which we have any knowl- 

 edge is a little water plant, a relative of the seaweed of today. 

 It was a simple organism, undeveloped as to roots, stem, or 

 leaf, but the struggle for life and food in its chosen environ- 

 ment was not intense and this lowly plant was able to survive 

 and reproduce itself abundantly in those far-off days of the 

 world's infancy. Geologists still find its fossil remains back in 

 the oldest rocks that show traces of any remains of life. Then 

 with the passing centuries, as conditions grew more varied, and 

 as life began spreading to various parts of the world, both ani- 

 mals and plants were faced with the necessity of keeping pace 

 with their surroundings. That is why we have so many kinds 

 of fishes, animals, and plants different environments, or dif- 

 ferent adaptations to the same environment have called into 

 being hosts of families and species each different one from the 

 other. As portions of 'the earth became colder, animals de- 

 veloped heavy fur to protect them; as other portions became 

 drier many plants found ways of storing up water in their 

 leaves and stems. One locality calls forth one characteristic, 

 another demands something entirely different. And just as we 

 find the ancestors of modern man had different characteristics 

 caused by different environment, so the ancestors of the mod- 

 ern tree are, for the same reason, profoundly varied in 

 appearance and in structure. 



It is here we touch one of the basic laws of life itself. For in 

 any study of plants or animals one is confronted over and over 

 again with the fact that all life is engaged in a perpetual task 



