FINAL REMARKS 499 
vertebrate kingdom itself, but the origin of the vertebrate from the 
most highly-developed invertebrate race. 
The study of the comparative anatomy of organs down to the 
finest details has always been a most important aid in finding out 
relationship between animals or groups of animals. My theory 
endorses this view to the uttermost, and especially indicates the 
study of the central nervous system and its outgoing nerves as that 
comparative study which is most likely to afford valuable results. 
As for the individual, so for the nation; as for the nation, so for 
the race; the law of evolution teaches that in all cases brain-power 
wins. Throughout, from the dawn of animal life up to the present 
day, the evidence given in this book suggests that the same law 
has always held. In all cases, upward progress is associated with 
a development of the central nervous system. 
The law for the whole animal kingdom is the same as for the 
individual. “Success in this world depends upon brains.” 
