38 Natural Salvation. 



cerebrum, a mass of highly organized cells which have 

 from long use and inherited development the capacity for 

 intelligent perception and thought." 



Without any attempt to present a consecutive line of 

 examples to illustrate the progressive development of the 

 cerebro-spinal system, the above outline indicates the prin- 

 ciple upon which this group of cells has come forward to 

 occupy its present grand prominence as exponents of 

 intelligence. 



In treating of the cells of the brain as individual, living 

 creatures, it may be well to set forth more explicitly what 

 their status of intelligence probably is, and explain how 

 far they may be regarded as sentient. It is not claimed 

 for any unicellular creature that it possesses rational 

 powers to such extent as is evinced by an organized tract 

 of cells like that of the human brain. For in the human 

 brain we find a great number of cells of four or more 

 varieties, devoted some to memory, some to reason or the 

 comparison of experiences, some to vision, some to hearing, 

 and some to the estimation of the odors and flavors ; and 

 it is the sentience and experience of them all which is 

 combined in the human intellect. Yet from observations 

 of unicellular life we find, as in the- case of ciliates, that it 

 is quite possible for a single cell, no larger than many of 

 the brain cells, to possess not only sentience, but to acquire 

 the data of memory, and to act from its previous experi- 

 ence. Many forms of unicellular life, indeed, behave 



