OBSERVATIONS ON THE CUCKOO. 57 
first time, and which, I need scarcely observe, cannot 
have been taught to it, at once distinguishes its sex. 
If a female, it is solicitous, after impregnation, to 
secure a suitable asylum for its offspring ; and here, 
though Darwin denies it, the operations of instinct 
are most strikingly manifested. Without any pre- 
vious instruction it discovers the nests of other birds, 
though it constructs none itself, by watching the 
birds build them; and selecting such only as from 
the size of the owners and their manner of feeding 
are best adapted to afford security to its eggs and 
proper nourishment for its young, it lays, just when 
the small birds themselves begin to lay, a single egg 
in each till it has produced its appropriate number, as 
if aware of the consequences which would ensue were 
two or more eggs deposited in the same nest. 
Having, in this hasty sketch, shown that the in- 
stinctiveness of the most remarkable propensities of 
the Cuckoo admits of direct proof, it follows that the 
notion of the peculiarities of this extraordinary bird 
being acquired must be relinquished as quite un- 
tenable. 
I may observe, in conclusion, that the history of 
the Cuckoo, by the evident marks of design which it 
displays in the admirable adaptation of means to 
ends, affords a convincing proof of the existence of a 
first principle of causation, the mysterious source of 
all that is good and beautiful in nature. 
