10 



Development of Mind 

 in Animals 



Nature has been more than generous in the preservation 

 of rehcs, living forms of archaic type which give us the op- 

 portunity to study not only the evolution of structure, but 

 also function and behavior. Fossils of extinct organisms usu- 

 ally show for our examination little more than skeletal 

 structure and never the soft tissue that makes up the nervous 

 system. It is almost wholly through the organization of the 

 nervous system, however, that progress in evolution is meas- 

 ured, and the importance of the living relics of evolutionary 

 primitive types cannot be exaggerated if we are to be per- 

 mitted our assumption that the process is oriented toward 

 greater conscious understanding. 



The essential processes involved in nervous action have 

 their roots in the general characteristics of protoplasm. In 

 the many-celled organisms these properties finally become 

 the specific activities of nervous tissue which is made up of 

 highly specialized cells called neurons. In the early evolu- 

 tion of multicellular animal types there is a gradual entry of 

 this neuron specialization, but in plants the evolutionary 

 trend never produced any cells specially assigned to nervous 

 activity. Nevertheless, plants are not without sensitivity. 

 They simply did not exploit this property of protoplasm, 

 but gradually emphasized structure and design toward 



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