Dr. Erasmus Darwin. 41 



and, like the Cambridge carrier's horse, able to draw 

 an inference. 



Besides, one awkward fact recently observed by 

 more than one person is that cuckoos have nested, or, 

 at all events, have been seen sitting on eggs ; from 

 which it is legitimately inferred that in days remote 

 and more favourable to the bird they did themselves 

 brood, and that in the cases of nesting observed we 

 have a reversion to true and original habit. The 

 supposition that the cuckoo, having laid an egg on 

 the ground, takes a good view of its colour, and then 

 looks round for a nest with eggs somewhat like it, is, 

 to our mind, so clumsy that it will not bear looking 

 at. Nor can we accept the theory that a species 

 should have come systematically to vary so much in 

 a fixed and uniform way through a range of indi- 

 viduals and their descendants. 



We are inclined to believe that there was more 

 power of mysterious adaptation than many would be 

 wiUing to credit. 



Dr. Erasmus Darwin expressed his belief, based on 

 observation, that the cuckoo sometimes hatches its 

 own young ; and Dr. Darwin gives an extract from a 

 letter of the Rev. Mr. Wilmot, of Morley, near 

 Derby, describing an instance brought to Mr. 

 Wilmot's notice in July, 1792, by one of his labourers 

 and afterwards watched by Mr. Wilmot himself, and 

 seen by many other witnesses, among them a Mr. 

 and Mrs. Holioake. Mr. Blackwall, indeed, dealt 

 critically with this case in the Zoological Journal for 

 1829 ; and urged that the witnesses one and all made 

 a mistake in thinking the bird a cuckoo, and that it 

 was a nightjar ; but this error was hardly possible to 



