ABSTRACT. 



By JOHN ALEXANDER NORTON, M.D. 



Read at the General Meeting^ November drd^ 1892. 



A PAPER was read upon the questions whether the 

 -^-^ coloration of birds' eggs is protective, and why the 

 cuckoo selects those nests in which she deposits her eggs. 



Passages were quoted from Seebohm, some of which were 

 written by Mr. Dixon, upon which Mr. Seebohm says, " This 

 chapter has been written for me by Mr. Charles Dixon, and 

 is sufficiently elaborate to post my readers up in the ques- 

 tions which have arisen on this subject, since it has been 

 regarded from the evolutionist point of view. The results 

 of the investigation are not quite so satisfactory as might 

 have been expected. There are so many cases which cannot 

 be explained by protective selection, that the student not 

 being able in this instance to fall back upon sexual selection, 

 is obliged to assume that many effects are the results of 

 extinct causes." 



The study of the cuckoo and her habits should show pro- 

 tective selection, if there is such a thing among birds, 



AVhat is the meaning of extinct causes as a factor in 

 Nature ? 



For the study of Oology birds' eggs have been divided into 

 two great classes, solely according to whether they are spotted 

 or white (or self-coloured), and these are sub-divided as to 

 whether they are laid in open or covered nests. 



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