138 Darwin and Romanes dealt with. 



pedient ; and the nest it makes being rather shallow, 

 the layer of fresh material, under which the, strange 

 eggs are buried, is built upwards above the rim of 

 the original nest ; so that the supplementary nest is 

 like one saucer placed within another." 



And the writer goes on to tell how, finding such a 

 nest one day, he tore off the upper bottom to find 

 three molothrus's eggs, two rotten, but the third with 

 a living embryo in it ready to hatch, which was very 

 lively and angry when, excluded from the shell, he 

 took it in his hand. He goes on to say : 



" The young tyrant-birds were about a fortnight 

 old, and as they hatch out only about twenty days 

 after the parent bird begins laying, this parasitical 

 egg, with a living chick in it, must have been deeply 

 buried in the nest for five or six weeks. Probably, 

 after the young tyrant-birds came out of their shells 

 and began to grow, the heat from their bodies, pene- 

 trating to the buried egg, served to bring the embryo 

 in it to maturity, but when I saw it I felt (like a 

 person who sees a ghost) strongly inclined to doubt 

 the evidence of my own senses." * 



Dr. Elliot Coues confirms this, remarking that 

 certain species of birds decisively reject the molo- 

 thrus's egg, and build a two-storey nest, leaving the 

 obnoxious egg in the basement. I want no better 

 proof that birds possess a faculty indistinguishable, 

 so far as it goes, from human reason. Instinct, in 

 the ill-considered current sense of the term, could 

 never lead a summer yellow bird up to building a 

 two-story nest to let a cow-bird's eggs addle below. 

 No question of inherited tendency here. I' 



* Birds of the Argentine, p 112. 

 ■^ Birds of North-West, p. 183. 



