ARTIFICIAL INCUBATION. 257 



claws it is able to scratch up roots from the ground 

 with great ease. " The composition of the mound," 

 says Mr. Gilbert, " appears to influence the colour- 

 ing of a thin layer with which the eggs are covered, 

 and which readily chips off, showing the true shell 

 to be white. Those deposited in the black soil 

 are always of a dark reddish -brown, while those 

 from the sandy hillocks near the beach are of a 

 dirty yellowish-white. The eggs differ a good 

 deal in size, but are alike in form, both ends being 

 equal. An average egg is three inches and a half 

 long by two and a quarter broad." A representa- 

 tion of one of these eggs, taken from a specimen 

 in the National collection, is represented on a 

 previous page. 



Artificial heat, as applied for the purposes of 

 incubation, assumes more importance when consi- 

 dered as an application of human industry. The 

 custom of hatching eggs by this method is one of 

 high antiquity. The Egyptians have long been 

 celebrated for the success which attended their 

 plans of artificial incubation; and it appears to 

 have been practised by them for many centuries. 

 The art was long confined to a certain district in 

 that country, where it was best understood, and 

 s 



