19^8.] by Birds of Eggs unlike iheh' own. 133 



throated Warbler (Apalis thoracica) accept au egg of 

 Sitagra ocularia. Later I found the egg lying spiked below 

 the nest, and the Warbler sitting. The Apalis eggs were 

 white with bold, scanty, red spots, and not far away was 

 another nest of tlie same species containing blue, closely- 

 freckled eggs just like miniature Stonechats'. I exchanged 

 an egg from each nest. I watched each Apalis accept the 

 other's egg ; but three hours later the first had rejected, 

 and the egg was lying spiked below the nest. Next day, 

 at noon, the second Apalis had not yet rejected ; so, 

 regarding it as an acceptance, I removed one of its own 

 eggs for an experiment of another kind. On returning 

 with it six hours later, I found the white, red-spotted egg 

 gone and the bird's own egg in sole possession. Other 

 cases occurred in experiments on Layard's Bulbuls. The 

 very fine discriminators already mentioned rejected an egg 

 of Lanius humeralis, accepted their own back, rejected an 

 egg of their own species but of another form, accepted 

 their own back, accepted instead an egg of their own form 

 from another nest, rejected one differing slightly from their 

 own form, accepted their own egg back, rejected the latter 

 on my painting on to it a few additional small markings, 

 widening the zone, rejected an egg of Colius striatus sub- 

 stituted for one of their two remaining eggs, did not 

 desert the one survivor, and accepted the other one back. 

 However, on my now substituting, for both these, two 

 eggs belonging to another form, they accepted them, as 

 already related. It was a very pretty experiment. 



Weavers {Hyj^hantornis jamesoni : vide figs, 3, 5, 7, 9, 

 12, 15) very freely and in several experiments rejected 

 eggs of their own species but not their own form. 



On the other hand, the pair of Bulbuls (P. layardi) that 

 had supplied one of the eggs rejected by the highly dis- 

 criminating birds — of the form shown in fig. 11 — had 

 accepted, instead of it, two other eggs of their own species 

 but belonging to quite different forms. 



8. Some birds accept anything. — This last-mentioned pair 

 of Bulbuls accepted also, and retained, an egg of Colius 



