236 THE REAL AND THE IDEAL 



CHAPTER XIV. 



THE DISTINCTNESS OF THE FIVE GRAND DIVISIONS. 



I THINK I have said enough already to convince you that I do 

 not advocate the possibility of a transition from one grand divis- 

 ion to another; and it is here that I shall probably disappoint 

 many who believe that there are no distinct types of form in the 

 animal kingdom. Even Lamarck advocated the distinctness of 

 certain types, and moreover he expressed a belief in the possi- 

 bility of discovering others. That there are certain ideal transi- 

 tions or relations between the Jive grand divisions, you must 

 have learned from the description of these diagrams of the ideal 

 types (figs. 55 to 64). Life is the first ideal relation among 

 them that impresses us ; then there is bilaterality, then bipolarity, 

 i. e., the opposition of above and below, and in more or less in- 

 timate relation with this is the tendency of the nervous system 

 to condense toward the side opposite the heart, and at the 

 same time to preponderate in the regions next the head. All 

 these are ideal, and are the expressions of a gradational prog- 

 ress from a lower to a higher type ; from an idea of low, un- 

 determined, diffuse organization, as in Protozoa, to the highest 

 degree of specialization and concentration, such as is to be seen 

 in the Vertebrates as a whole, and in Man; in whom the crown- 

 ing effort was centered on the brain, the throne of thought, 

 before which all the other faculties stand in inferior ranks. 



Now if these which I have called " ideal relations between 

 the great types" were not so, but rather real relations, i. e., rela- 

 tions of consanguinity, we ought to be able to trace the organi- 

 zation of an animal of one type into that of another ; and in 

 order now to show that this cannot be done, I shall proceed to 

 make comparisons between the types of the grand divisions, as 



