NIDIFICATION AND INCUBATION 343 



hours, if not for days. Timid as is the Gannet in 

 winter time, it will now permit a human being to 

 approach within a few yards of its nest, all thought of 

 self-preservation giving way to the parental instinct. The 

 egg of a Gannet is white when laid, with a chalky 

 coating like the eggs of Shags, Pelicans, Darters and 

 Frigate-Birds,* and the surface of its sheU is often creased 

 and wrinkled, a character well shown in Mr. Wilson's 

 drawing.! This outer calcareous jacket can be easily 

 scraped off the egg, when the shell will be found to show 

 a green tint, especially when held up to the light. This is 

 in reality, as Mr. R, Drane has pointed out, a greenish 

 shade obtained by means of transmitted light, J the 

 lining or follicular membrane being white, and from this 

 the shell can be easily separated. Lime is a valuable 

 ingredient in the formation of an egg-shell, and Mr. Drane 

 has shown that Gannets and other sea-birds obtain lime 

 from the fish, of which they eat such large quantities. § 



* But not like the Tropic-bird's egg, which is spotted, in which it 

 differs from the other Steganopodes. 



t Similarly the egg of the Emperor Penguin is sometimes covered 

 with chalky nodules (" Nat. Antarctic Expedition," 1901-4). 



+ " Cardiff Naturalists' Society," 1893-4, p. 8. 



§ With a view of demonstrating that there was lime in a fish ho burnt 8 ozs. 

 of sprats in a Hessian crucible until they were reduced to 140 grains of black 

 ash, and this sediment he further reduced in a platinum cajisule to 78 grains 

 of pale ash, which he found to be phosphate of lime. After weighing an emjity 

 Gannet's egg he concludes that it would only require the lime derivable 

 from 1 lb. of fish to form one (" Cardiff Naturalists' Society," 189,3-4, p. 12). 



