286 Cuculidce. 



pregnable. Facts are proverbially stubborn things, and not to bo 

 overthrown by opinions held only from the force of habit and not 

 from conviction of their truth. 



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 judg- 

 ment and deep scientific attainments ; it is the result, moreover, 

 of patient research, and a long course of inquiry among men 

 well calculated to form a right conclusion. At all events let 

 the theory be well understood: for some have ignorantly or 

 maliciously declared that Dr. Baldamus had given out that the 

 Cuckoo had the power of laying her egg of what colour she 

 pleased, which is exactly the contrary of what the Doctor had 

 stated. A great deal of controversy and some rather warm con- 

 tention arose between those who accepted and those who 

 rejected the theory ; but, as I introduced the subject to the pages 

 of the Zoologist, I was permitted to sum up the evidence at the 

 close of the discussion ; and I now proceed to state what con- 

 clusions I arrived at after a careful examination of the several 

 opinions expressed. 



(1) I felt no hesitation in submitting that the balance of 

 opinion favours tho theory that the eggs of the Cuckoo do vary 

 in colour to a considerable extent, but I hastened to add that 

 there are some, and good ornithologists too, who deny this, and 

 who even declare that the eggs of the Cuckoo are of peculiarly un- 

 varying colour; but it will not be disputed that those who so 

 think, or at all events who have so declared their opinion, are in 

 a very small minority. 



(2) I submitted that it was very generally allowed that the eggs 

 of the Cuckoo strangely resemble the eggs of other birds, 

 especially those among which the egg of the Cuckoo is frequently 

 found. In the view of the German ornithologists, this is thought 

 to be the rule, though that view is qualified by the addition that 

 * to this rule there are very many exceptions' In the opinion of 

 most of our English ornithologists, however, it seems to be con- 

 sidered that the rule is in favour of the colour generally (perhaps 



