ANIMAL INSTINCTS. 159 



adapted to meet casual interferences with the instinc- 

 tive life of the species, and they might doubtless be 

 variously multiplied by research in this direction that 

 is, by direct experiments made to determine how far, 

 and by what methods, instincts interfered with may be 

 supplemented by the resources, call them what you 

 will, of the animal itself. Such experiments would be 

 as curious as instructive. They are the rather to be 

 recommended from the paucity of other means of 

 entering into the depths of the question. The careful 

 observation of the instincts of hybrids, and of the mixed 

 breeds from varieties of the same species, is one of 

 other collateral paths of enquiry, yet only partially 

 pursued, all in the right direction, but all stopping 

 short of those ultimate truths upon which alone a true 

 theory of instincts can rest. 



In the paper before referred to I have spoken in 

 some detail of the nervous system as that part of the 

 animal organisation which, though instrumentally only, 

 ministers most directly, it would seem, to the pheno- 

 mena of instincts. The experiments which show the 

 impairment or abolition of certain instincts by special 

 injuries of the brain or spinal nerves, or even of the 

 antennas of insects, prove undoubtedly the ministration 

 of these parts to the functions in question. They also 

 render it probable, as do other considerations, that the 

 excitement, direction, and catenation of instinctive acts 

 are fulfilled directly through the nerves ; and very 

 especially through that system of ganglionic nerves, 

 which in its functions, direct or reflex, so largely con- 

 trols every part of organic life. The absence of any 



