Life-history of the Cuckoo. 129 
invests every hen Cuckoo with the faculty of laying eggs, coloured 
like the eggs of the bird, of whose nest she prefers to make use, 
according to the locality; or in other words; every hen Cuckoo 
lays eggs only of a fixed colour, corresponding with the eggs of 
that warbler, in whose nest she lays them (as a general rule): and 
she only lays in other nests, when at the time for her laying, one 
of the species, of her own peculiar type, as we may say, which is 
fitted for her in every particular, is not ready.’’] 
Such is the very interesting and well sustained argument of Dr. 
Baldamus: and however new and startling his hypothesis, however 
_ unprecedented his conclusions, yet he supports his argument with 
' such a battery of facts that his position seems almost impregnable. 
_ Facts are proverbially stubborn things, and not to be overthrown 
_ by opinions held only from the force of habit and not from conviction 
of their truth. At the same time I am far from advocating any 
_ acceptance of conclusions, until we have tried them and ascertained 
their value. And so I would urge upon every outdoor observer, 
_ (and everybody who lives in the country ought to be an out-dvor 
4 observer) to assist in investigating this curious question, and I 
i would invite them to communicate to this Natural History Society 
eeny discoveries they may make, or any well ascertained facts they 
_ may elicit. We have a new point before us in the history of the 
_ Cuckoo suggested for our consideration: we all hear the Cuckoo’s 
ery every spring all around us: we know then that the bird is with 
us, laying its eggs in our neighbourhood: it requires only diligence 
and observation and patience to make us acquainted with its habits. 
But yet again I would repeat the caution against rushing too 
quickly to conclusions: it is not an isolated fact here or there that 
would warrant any inference: it is only by careful comparison of 
many well authenticated particulars, that we are able to arrive at 
any satisfactory decision. While on the other hand, the question 
before us is not to be set on one side as the dream of an enthusiast, 
or the fancy of a superficial naturalist. It is deliberately proposed 
by a leading ornithologist, of mature judgment and deep scientific 
a attainments: it is the result moreover of patient research, and a 
= course of enquiry among men well calculated to form a right 
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