172 THE POPULAR SCIENCE MONTHLY, 



lar system. For the present I neglect the absolute distinction there 

 really is between mental and nervous states. 



Beginning with evolution, and dealing only with the most conspic- 

 uous parts of the process, I say of it that it is an ascending develop- 

 ment in a particular order. I make three statements, which, although 

 from different stand-points, are about the very same thing : 1. Evolu- 

 tion is a passage from the most to the least organized — that is to say, 

 from the lowest well-organized centers up to the highest least organized 

 centers. Putting this otherwise, the process is from centers compara- 

 tively well organized at birth up to those, the highest centers, which are 

 continually organizing through life. 2. Evolution is a passage from the 

 most simple to the most complex ; again from the lowest to the high- 

 est centers. There is no inconsistency whatever in speaking of centers 

 being at the same time most complex and least organized. Suppose a 

 center to consist of but two sensory and two motor elements, if the sen- 

 sory and motor elements be well joined, so that " currents flow " easily 

 from the sensory into the motor elements, then that center, although 

 a very simple one, is highly organized. On the other hand, we 

 can conceive a center consisting of four sensory and four motor ele- 

 ments, in which, however, the junctions between the sensory and the 

 motor elements are so imperfect that the nerve-currents meet with 

 much resistance. Here is a center twice as complex as the one pre- 

 viously spoken of, but of which we may say that it is only half so well 

 organized. 3. Evolution is a passage from the most automatic to the 

 most voluntary. The triple conclusion come to is, that the highest 

 centers, which are the climax of nervous evolution, and which make 

 up the " organ of mind," or physical basis of consciousness, are the 

 least organized, the most complex, and the most voluntary. So much 

 for the positive process by which the nervous system is "put to- 

 gether " — evolution. Now for the negative process, " the taking it to 

 pieces " — dissolution. 



Dissolution being the reverse of the process of evolution just spoken 

 of, little need be said about it here. It is a process of undevelopment ; 

 it is a "taking to pieces "in the order from the least organized, the 

 most complex, and the most voluntary, toward the most organized, 

 most simple, and most automatic. I have used the word " toward," 

 for if dissolution were up to and inclusive of the most organized, etc., 

 if, in other words, dissolution were total, the result would be death. I 

 say nothing of total dissolution in these lectures. Dissolution being 

 partial, the condition in every case of it is duplex. The symptomatol- 

 ogy of nervous diseases is a double condition ; there is a negative and 

 there is a positive element in every case. Evolution not being entirely 

 reversed, some level of evolution is left. Hence the statement " to 

 undergo dissolution " is rigidly the equivalent of the statement " to be 

 reduced to a lower level of evolution." In more detail, loss of the 

 least organized, most complex, and most voluntary implies the reten- 



