112 CELL INTELLIGENCE THE CAUSE OP EVOLUTION 



the various tissues of the vegetable body. These cells, 

 which we shall hereafter consider more closely, are inde- 

 pendent living beings, the citizens of the state, which con- 

 stitute the entire multicellular organisms. We thus have 

 before us a highly complex apparatus, the more minute 

 structure of which we have hardly begun to know, even 

 with the help of our strongest microscope and the signifi- 

 cance of which we rather guess than know. Its complex 

 mechanism is capable of the most intricate psychical 

 functions. But even this elementary organ of mental ac- 

 tivity of which there are thousands in our brain, is only 

 a single cell. Our whole intellectual life is but the sum 

 of the results of the activity of all such nerve cells or mind 

 cells." 



The living structures that we see include all those 

 things containing life such as plants, trees, insects, ani- 

 mals, birds, fish, etc. They are all produced by the cell. 

 They are constantly changing, a fact which proves that 

 the builders are all the time trying to improve their habi- 

 tation in order to meet some climatic or other condition, 

 or obtain some advantage in one way or another in the 

 struggle for existence. By reason of this fact, the scien- 

 tists have decided that it is impossible to classify them as 

 animals and plants because they overlap each other so 

 gradually that it is impossible to tell where the one be- 

 gins and the other ends. We might classify them gen- 

 erally as either movable or as stationary structures. The 

 plant building cells usually build stationary structures be- 

 cause they are able to make their own food and building 

 material by the aid of sunlight from the raw material of 

 earth, air and water. The animal building cells on the 

 other hand being compelled to move about in search of 

 food build movable structures. The classification would 

 not in all cases be correct, as some plants have movable 



