12 UNITY IX LIFE. 



///. Individuality. No two organisms are exactly 

 alike. 



IV. Self -activity. Development of structures de- 

 pends on the exercise of functions. 



V. Natural Selection. The survival of the fittest 

 in the struggle for existence. 



VI. Mutual Help. The race not to the swift nor 

 the battle to the strong, but to those who can keep to- 

 gether. 



VII. Isolation. Effects of individual separation from 

 bodies of organisms. 



The interaction on protoplasmic structures of these 

 factors or groups of forces and of others more or less 

 known the cause of Organic Evolution. 



