Evolution 



root of all the plain and obvious distinctions between animals 

 and plants. The plant has neither the necessity to go forth in 

 search of its food materials, which nature brings to it, nor has it 

 to spare of its painfully collected energy for the labour of locomo- 

 tion. Hence it remains stationary. The animal must of necessity 

 go to seek its more elaborate fare, therefore it moves. More- 

 over, to be successful in its search, the animal obviously requires 



Fig. 21. — Amoeba. 

 A', Nucleus ; F, contractile vacuole. 



a nervous system to direct and control its movements, which 

 system, except in the simplest and crudest forms, is absent from 

 the plant. In the main, then, the plant builds up and saves, the 

 animal breaks down and spends. The plant is the producer, 

 the animal the consumer. 



Turning now to those of the lower organisms that are somewhat 

 more definitely animal in nature, we may describe the common 

 Amoeba. Microscopic in size, this creature consists of a speck of 

 semi-liquid protoplasm, which is irregular and ever-changing in 



30 



