THE CUCKOO. 27 



earlier departure, the adult Cuckoos leave their young to find 

 their way south by themselves. They are, however, by no 

 means the only birds which act thus. 



The history of the young Cuckoo in the nest of the foster- 

 parents is that, being hatched about the same time as the young 

 of the rightful occupant, the interloper, while still blind and in 

 an apparently helpless condition, manages to hoist the other 

 little blind nesthngs over the side of the nest, so that they 

 perish, and it endures to receive the unremitting care of the 

 pair of small birds, in whose nest the mother Cuckoo may have 

 placed her egg. This story was first related by Dr. Jenner, to 

 whom we owe the discovery of vaccination, and we have heard 

 that some " anti-vaccinationists " have carried their fanaticism 

 so far, that, from their dishke of the founder of the practice of 

 vaccination, they would wish to throw doubts on the authen- 

 ticity of Dr. Jenner's observations on the habits of the Cuckoo ! 

 Some few years ago, however, the proceedings of the young 

 Cuckoo, in ejecting from the nest its young foster-brothers and 

 sisters, were observed by Mrs. Hugh Blackburn, who sketched 

 the operation. We do not know whether the anti-vaccination- 

 ists wish to accuse this lady of an untruthful record, but they 

 will scarcely be inclined to doubt the evidence of the late Mr. 

 John Hancock, who also was a witness to the method of the 

 young Cuckoo in ejecting the other occupants of the nest (Tr, 

 North, and Durham Nat. Hist. Soc. viii.pt. 2, pp. 210-217, 1886). 

 The fanatics may not even be satisfied with this evidence, but 

 it will be sufficient for every ornithologist. 



The small size of the egg laid by the Cuckoo, considering 

 the bulk of the bird, is another peculiar feature in its economy. 

 Great diversity of colour, also, is one of its characteristics, and 

 considering the various types of eggs laid by the Cuckoo, it is 

 not wonderful that the theory exists that the bird places its egg 

 in the nest of a species, the eggs of which most resemble its 

 own in colour. That there is great truth in this theory I 

 firmly believe, otherwise it would be difficult to account for the 

 fact that blue Cuckoo's eggs should be placed in the nest of 

 a Redstart, which likewise lays blue eggs. In the British 

 Museum are such clutches of eggs, and also blue eggs placed 

 in the nest of a Pied Flycatcher, the eggs of which are also 

 blue. The fact of the Cuckoo producing a blue egg was for 



