The Zoologist — March, 1868. 1117 



I. " Nature must have some special motive in the circumstances 

 above detailed, so many, so connected together, but so peculiar. 



II. That motive is plainly to be seen ; viz. that by meaus of certain 

 laws originally made she may ensure and facilitate the preservation of 

 a species otherwise much exposed to danger. 



III. She attains this end by a very simple method : in that she 

 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 w r ould urge upon every out-door observer (and 

 everybody who lives in the country ought to be an out-door observer) 

 to assist in investigating this curious question, and I would invite 

 them to communicate to this Natural History Society any 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 cry every spring all around 

 us ; we know then that the bird is with us, laying its eggs in our neigh- 

 bourhood : 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 attainments : it is the result, moreover, of patient 



