THE CIRCLE OF LIFE 



and roots and in a thin shell about the plant, beneath the 

 bark. The inner, older parts of the plant become hard and 

 rigid, and lose their power of growing. (See Figure 1.) 



It is somewhat 

 different in most 

 animals. They 

 grow as the little 

 pig which "died in 

 clover," that is to 

 say they grow "all 

 over." In them all 

 the cells, with 

 some exceptions, 

 divide and grow. 

 There are no spe- 

 c i a 1 regions of 

 growth. 



With all the dif- 

 ferences in growth, 

 however, all growth 

 is alike in that it is 

 ^ -^ due to the fact that 



Figure 1. Lengthwise section through a growing some of the cells 

 root tip of a plant. From Coulter's Plant Life and take in water and 



Plant Uses. foods, and expand. 



These cells may divide many times and continue to expand 

 after each division. 



5. Immaturity. The period of growth comes early in 

 life in those organisms that grow all over. Presently it 

 ceases. In those whose growth is local, it continues 

 throughout life, but it is always in the youngest parts. 

 Growth is thus always a sign of immaturity. During 

 growth the upbuilding processes are more powerful and 

 rapid than the destructive. The length of the growth 

 period in plants and animals differs as much as the length 

 of life itself. These periods correspond in length. If the 



