STEM STRUCTURE 



83 



the organic world, which now towers higher than a twenty-story 

 building and is still growing. Some animals, such as the elephant, 

 may live two hundred years, but even these, or man, with his three 



Courtesy of the American Museum of Natural History. 



FIG. 20. Section of one of the big trees of California, the " Mark Twain," 

 16 ft. in diameter, and 1341 years old. 



score years and ten, are the merest infants beside such ancient 

 inhabitants of the vegetable world. 



This illustrates a fact which is often overlooked, that perennial 

 plants really have no limit of growth, as do animals, but keep on 



