18 INSTINCT 



Instinct aided by reason, as in the taylor-bird 1 . 

 Taught by parents, cows choosing food, birds singing. 

 Instincts vary in wild state (birds get wilder) often 

 lost 2 ; more perfect, nest without roof. These 

 facts [only clear way] show how incomprehensibly 

 brain has power of transmitting intellectual opera- 

 tions. 



Faculties 3 distinct from true instincts, finding 

 [way]. It must I think be admitted that habits 

 whether congenital or acquired by practice [some- 

 times] often become inherited 4 ; instincts, influence, 

 equally with structure, the preservation of animals; 

 therefore selection must, with changing conditions 

 tend to modify the inherited habits of animals. If 

 this be admitted it will be found possible that many 

 of the strangest instincts may be thus acquired. I 

 may observe, without attempting definition, that an 

 inherited habit or trick (trick because may be born) 

 fulfils closely what we mean by instinct. A habit is 

 often performed unconsciously, the strangest habits 

 become associated, d. tricks, going in certain spots 

 &c. &c., even against will, is excited by external 

 agencies, and looks not to the end, a person playing 

 a pianoforte. If such a habit were transmitted it 

 would make a marvellous instinct. Let us consider 

 some of the most difficult cases of instincts, whether 

 they could be possibly acquired. I do not say 

 probably, for that belongs to our 3rd Part 5 , 1 beg 

 this may be remembered, nor do I mean to attempt 

 to show exact method. I want only to show that 



1 This refers to the tailor-bird making use of manufactured thread 

 supplied to it, instead of thread twisted by itself. 



2 Often lost applies to instinct : birds get wilder is printed in a paren- 

 thesis because it was apparently added as an after-thought. Nest without 

 roof refers to the water-ousel omitting to vault its nest when building 

 in a protected situation. 



3 In the MS. of 1844 is an interesting discussion on faculty as distinct 

 from instinct. 



4 At this date and for long afterwards the inheritance of acquired 

 characters was assumed to occur. 



5 Part II. is here intended : see the Introduction. 



