160 ANIMAL INSTINCTS. 



brain in many large classes of animals whose instincts 

 are absolute and complete, makes it indeed necessary 

 that we should look to these ganglia and nervous cen- 

 tres of the trunk as the structures coming into closest 

 connexion with them ; while to maintain this view 

 throughout we must suppose some inscrutable form of 

 nervous matter in the lowest types of life, where the 

 instincts are strongly marked, though no such matter 

 can be detected. 



It will be seen what various unsolved questions 

 beset every part of this great problem. Still the rela- 

 tion just denoted carries us a step forward in the en- 

 quiry, by associating the instincts which bind animal 

 life to the outer world with those peculiar internal 

 organisms which instinctively serve to the maintenance 

 of life itself. It is one of the great prerogatives of 

 science to advance itself through these secondary rela- 

 tions, even where the ultimate problem lies beyond 

 reach. 



If material organisation tells us so little on which 

 to frame a true theory of instincts, still less can we 

 seek this by an appeal to those powers, or forces, as 

 they are termed light, heat, electricity, &c. which 

 act on matter universally, and not least under its or- 

 ganic forms. Life, indeed, could not exist, or its func- 

 tions be maintained, apart from these forces, which 

 minister to instincts as to other vital actions. Still it 

 is excitement and ministration only, and no solution of 

 the mystery. Nor do we gain more by bringing the 

 ' vital principle ' to our aid, which here, as elsewhere, 

 is a barren phrase, veiling our real ignorance. 



A special work on instiacts, based on larger com- 



