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Vol. XXXIX 1922] picture operator in a blind and secure a film of the performance, including the removal of a Pipit's egg by the Cuckoo, which seems normally to follow the deposit of its own egg.

The Cuckoo's exact method of depositing her egg seems not to have been even yet positively ascertained. Mr. Chance construes his evidence as proving that an egg can be laid in eight seconds, the period that the bird under observation was actually on a nest and left and egg which was not there before, and he also claims that in other instances it can be retained for hours after the bird has become anxious to lay it. Mr. Stuart Baker in a valuable paper on this subject, (Bull. Brit. Ornith. Club. March 13, 1922,) regards both of these claims as improbable and says "there is no doubt that in the vast majority of cases the egg is laid by the Cuckoo elsewhere, and deposited by means of the bill in the foster-parent's nest," and further suggests that she holds her egg in her gullet and regurgitates it into the nest. He actually interprets Mr. Chance's film as endorsing this view.

Mr. Baker's admirable paper should also be read with care especially as it deals with African and Asiatic Cuckoos which must obviously be considered in solving the broader problems of the Cuckoo's parasitism.

Mr. Chance is certainly to be congratulated upon his admirable work and the great progress that he has made in the attempt to solve "the Cuckoo's Secret."—W. S.