IS NEST-BUILDING AN INSTINCT IN BIRDS? 
277 
habit, in a state of nature, of starting the nest on branches 
above their heads. As soon, however, as a few branches had 
lodged below them, they finished the nest, which accident had 
commenced for them. Thirdly, they followed the habits of the 
species to which they belong, although it is probable that these 
habits had been in abeyance for many generations, and certainly 
they had been in abeyance for more than one generation. 
Fourthly, the conditions were present which would have enabled 
them to breed in the same kind of nest as that in which they 
were themselves brought up, and in which they had already 
reared a young bird. Lastly, these birds were very tame, so 
that if new conditions could have modified their natural habits, 
this was a case in which we might have expected modification, 
as all the circumstances were in favour of a perversion of natural 
habits. 
I do not know how to account for the fact that these birds 
built a natural nest. And I may be hasty in my conclusion, 
but I am in my own mind convinced that we have here an instance 
of what is usually called Instinct. This conviction is the more 
important because it is not a year ago since I gave a lecture in 
Great Ormond Street, at the Working Men’s College, in which 
I maintained the view that animals act in such cases entirely 
by reason and experience ; and at that time I felt certain from 
all I knew that Mr. Wallace was right, or nearly right, in his 
views. 
The whole phenomenon had a striking similarity to the slow 
return of memory, brought about by a series of associations. 
There can be no doubt as long as the birds remained in a com- 
paratively confined space, without the use of their wings, and 
without a natural branching tree to build in, they would never 
have built a characteristic nest. My own belief is, that the tree 
acted as a stimulus to their instinct, and that the natural sur- 
roundings prompted them, as it were, and awakened their dor- 
mant inherited powers. Although my impression is, that the 
final site of the nest was determined by the place where the 
sticks fell, which they failed to fix above them, I am by no 
means assured in my own mind that even this was not deter- 
mined by a subsequent awakening of an instinctive act, and 
that the sticks were intentionally dropped upon the branch 
below them. The want of readiness in some things which these 
birds exhibited at first can hardly be considered surprising, 
when we remember the number of generations in which it is 
probable no natural nest had been built. Indeed, it is quite 
possible, and I think even probable, that their progenitors had 
laid their eggs on hay or straw on the floor of a dove-cot for 
fifty years or longer. 
The importance of these facts can hardly be over estimated, 
