NIDIFICATION AND INCUBATION 355 



Duration of the Incubatory Period. — The incubation of 

 birds is a subject which had been greatly neglected until, 

 in 1890, it was taken in hand by Mr. William Evans, of 

 Edinburgh ; but, thanks principally to him, Ave now know 

 much more about the period of its duration in different 

 genera of birds than was formerly the case. What we know 

 of the Gannet is briefly as follows : — 



First, an egg laid on April 22nd, 1910, at the Bass Rock, 

 and inscribed by Mr. Campbell with the date, was hatched 

 on June 5th — forty-four days."* 



Secondly, Mr. E. T. Booth puts the incubating period at 

 from forty-three to forty-five days, taking his data from the 

 young ones bred in his garden at Brighton, f 



Thirdly, Mr. W. Evans puts it at rather less, a Gannet's 

 egg which he put under a hen having hatched on the 

 thirty-ninth day, while another had a live chick in it on 

 the forty-second day. J Forty-two days agrees with the 

 opinion entertained by the Rev. Neil Mackenzie of St. Kilda,§ 

 and also with that of the German naturalist Naumann]|, 



* "The Scotsman," July 25th, 1910. 



t " Rough Notes," Vol. III. 



X " Ibis," 1891, p. 69. 



§ " Annals Scot. Nat. Hist," 1905, p. 144. 



11 " Nat. der Vogel," XI., p. 44. 



z 2 



