NERVOUS SYSTEM OF VERTEBRATES. 83 



the process of evolution and usually accompanied with 

 transfer headward. 



In- the process of development, whether in the evolu- 

 tion series, or in the taxonomic series, or in the embry- 

 onic series, we observe the same order. Organisms are 

 at first unmodified cell-aggregates. From such aggre- 

 gates tissues performing different functions are differ- 

 entiated. From this time onward cephalization begins. 

 Among the tissues there is a gradually increasing domi- 

 nance of the highest, the controlling tissue, viz., the 

 nervous tissue. Then in the nervous tissue a gradually in- 

 creasing dominance of the highest part, viz., the brain. 

 Then in the brain a gradually increasing dominance of 

 the highest ganglion, viz., the cerebrum. Then in the 

 cerebrum a gradually increasing dominance of the high- 

 est substance, the surface gray matter, as shown by the 

 complexity of the convolutions. And, lastly, among the 

 convolutions a gradually increasing dominance of the high- 

 est, viz., those in the frontal lobe, as shown by the 

 position of the fissure of Rolando. In all there is an 

 increasing dominance of the higher over the lower, and 

 of the highest over all. This is everywhere the law of 

 evolution. 



Shall it stop here ? Shall it not be carried forward 

 on a higher plane by the conscious effort of man ? Is 

 not all civilization, all culture, all education a voluntary 

 process of cephalization ? Here, also, there must pre- 

 vail the same law of progressive domination of the 

 higher over the lower, of the distinctively human over 

 the animal, of mind over body; and, in the mind, of the 

 higher faculties over the lower, the reflective over the 

 perceptive, and of the moral character over all. In all 

 your culture be sure that you strive to follow this law 

 of evolution. 



