450 JOURNAL, BOMBAY NATURAL HISTORY SOCIETY, Vol. XV. 



yellowish green absolutely without a mark. With regard to these last, 

 had I not — as. indeed, I have with every clutch of the tree-pie — observed 

 the bird not once, but several times on the nest, and seen the eggs lifted 

 out from under her, I would not have believed in their parentage." 



In face of facts such as these I maintain that it is impossible 

 to hold that the eggs of this bird are protectively coloured. 



The eggs of all the mynas are blue, yet the nesting habits of the 

 various species differ greatly. The common myna (Acridotheres tristis) 

 nests in holes in the walls of buildings, A. fuscus builds in holes in wells 

 or river cliffs, while the pied myna (Stornopastor contra) builds its nest 

 in a tree. I maintain that it is almost inconceivable that the eggs of each 

 of these species should need the same protective colour. . 



The mynas do not form an isolated instance. It may almost be 

 stated as a general law that the eggs of nearly allied birds resemble one 

 another even though the nesting habits of the species vary considerably. 

 This alone is sufficient to disprove the protective theory. 



Before leaving this hypothesis I may note one other fact for which 

 it is unable to account. With birds that lay only two eggs it often 

 happens that nearly all the colouring matter is imparted to one only, the 

 other being left almost unpigmented. 



The third theory need not detain us long. It has apparently been 

 put forward only, because the first two theories are so unsatisfactory. 

 The hypothesis that the colour of the eggs is determined by the influence 

 of the surrounding tints on the retina of the female is said to account 

 for the fact that eggs laid in dark places are white ; the female while 

 laying them sees no colours to impress her. The red splashes on the 

 eggs of birds of prey are supposed to be due to the sight of blood. 

 The fact that cuckoo's eggs often resemble in colour those of the host is 

 likewise asserted to be due to the influence which the sight of the eggs 

 already in the nest exerts upon the female. This appears to constitute 

 the sum total of the evidence in favour of this theory. Not only is the 

 evidence altogether inadequate and most unconvincing ; but the theory is 

 obviously incapable of explaining hundreds of phenomena of egg coloura- 

 tion — phenomena which it would be wearisome to detail. I submit tliat 

 two of the above theories may be unhesitatingly rejected, while the 

 remaining one is able only to explain the phenomena of the colouration of 

 birds' eggs in certain cases. Whether it will ever be possible to explain 

 all the various markings on birds' eggs, it is impossible to say. It seems 



