LiVING ORGANISMS 27 



structure. After its separation from the 

 parent body, it is capable of independent exist- 

 ence, and, under favourable circumstances, 

 of developing into a new individual, in most 

 respects similar to that from which it derived 

 its origin Living beings form a continuous 

 series, from the first appearance of life on the 

 earth until now. The offspring have usually 

 characters which they have inherited from 

 their parents, but they may develop new 

 characters which may arise from new cir- 

 cumstances affecting them during their own 

 lives. If these characters, either inherited 

 or acquired, are transmitted to descendants, 

 the phenomenon is known as heredity. Each 

 living being shows a period during which 

 there is a maximum vital activity, when the 

 liberation of energy is greatest. During life 

 it passes by stages up to this period ; then, 

 after a stage of maximum activity, the 

 powers of the organism slowly decline. 

 During its life an organism undergoes change 

 of form, there is increase of mass, and it shows 

 increasing complexity of structure. These 

 changes, however, do not go on indefinitely. 



