524 CLASS AVES. , 



birds in favour of the cuckow alone, is evidently commanded 

 by an imperious law of nature, for the majority of these 

 birds will not cover other eggs beside those of the cuckow. 

 Lothinger tried a number of experiments in this way, the 

 result of which proved the fact now stated. 



«0n the 15th of May, 1772," observes this naturalist, 

 " about four in the morning, I put an egg of the gold-crested 

 yrren into a nest of the common warbler, which was concealed 

 in some nettles, pretty near the ground, and in which were 

 five eggs, which the warbler had been hatching for some 

 time. I remained in the neighbourhood, to be certain that 

 nobody should lay hands on the nest ; but in about a quarter 

 of an hour or so, I could no longer find the egg which I had 

 placed there. I again stole into this same nest a thrush''s 

 egg. About five in the evening this egg occupied the centre 

 of the nest, and it appeared from its position as if it was the 

 intention of the warbler to hatch it ; but the following morn- 

 ing it had disappeared. I looked for it, and found it on the 

 ground, open and dry. It had either been broken in its fall, 

 or the bird had opened it to get rid of it more easily. On 

 the same day, in the afternoon, I took an egg from the nest of 

 a blackbird in the neighbourhood, and placed it, still quite 

 warm, in the nest of the warbler, which was then absent, though 

 but for a little time, as her eggs had still a remarkable 

 degree of heat. Them I removed, and, imitating the cuckow, 

 left only the blackbird's egg in the nest. After some minutes 

 I approached, and saw the warbler hatching as usual. The 

 following day, returning to the same spot, I found the nest 

 abandoned, and, as is customary with the warblers on the 

 failure of a brood, the birds were already disposing them- 

 selves for the construction of another. 



*' About the end of June, I removed from the nest of a 

 bunting four eggs, which the bird had been hatching for a 

 long time, and I put one of a blackbird in their place. Two 



