10 THE ORIGIN OF MAN 



dom or Animal Kingdom. The entities occur- 

 ring in the inorganic world are in the crystalline 

 form, or in the fragmental or altered condition; 

 while the bodies of living matter have their sub- 

 stance organized into a mechanism capable of 

 response to external and internal agencies, and 

 are hence called organisms. 



A living organism exhibits five inherent activ- 

 ities — contractility, the power of movement, 

 which is better developed in animals, than in 

 plants; irritability, the power of responding to 

 stimulus in the wide sense, also more marked in 

 animals ; nutrition or the utilization of food ; res- 

 piration ; and excretion, which is again greatest in 

 animals — besides the periodic activities of growth 

 and reproduction. 



These manifestations of living matter are seen 

 even in the simplest of plants and animals, where 

 the individuals are microscopic in size and the 

 unit is contained in a single cell. However, liv- 

 ing matter is more commonly seen and compre- 



