The Oologists' Record, June i, 1922. 45 



any shadow of doubt, that the Cuckoos under his observation did 

 find thfe nests of their victims two or three days before the laying 

 of the eggs in such nests, and also that they were able to retain 

 their eggs for a considerable time if there were no suitable nests 

 ready to receive them. 



It is well known that at certain seasons a domestic hen will 

 be found to have a string of little immature eggs forming and that, 

 given the favourable conditions required for their maturity, the 

 laving of them follows as a matter of course. It might be supposed, 

 therefore, that a female Cuckoo has her eggs forming in the same 

 wa5^ possibly before her arrival in this country, and "that, favoured 

 with certain climatic and dietetic conditions, she will have them ready 

 for extrusion at a certain time and deposit them in the nests of her 

 favourite fosterers or, failing such, in other nests, without being 

 stimulated in the manner suggested. 



But Mr. Chance has worked in such a mass of data in support of 

 his theories that it is hardly fair to criticise any of them without 

 (luoting the context more fully, and we feel sure that the bulk of our 

 readers will read the book for themselves and, having done so, 

 communicate to Mr. Chance any data they possess which helps to 

 clear up any point in the problem, and in future avail themselves 

 of every opportunity of securing more. Any one of them may, 

 unwittingly, stumble on facts which will help him in his studies. 



Mr. Chance does not, as so many of his predecessors in this field 

 have done, suggest any reason why the Cuckoo is a parasite ; and 

 this led us to turn to " The Evolution of Sex," by Professors Geddes 

 and Thomson. After dealing with the Cuckoo question very fully, 

 the authors come to the conclusion that the habit " is a deliberate 

 expression of the whole constitution of the bird." But among the 

 many characteristics which they attribute to the species, we suggest 

 that the real reason may be found in the fact that, as the authors 

 point out, " . . ; even among greedy birds, the Cuckoos hold 

 a verv high rank. They are remarkably insatiable, hungry, 

 gluttonous. Even the anatomical conditions asserted by some to be 

 important, the swollen low-set stomach, may have their influence 

 in the Cuckoo, which has certain other peculiarities, though the 

 same conditions may be overcome in other birds, which remain 

 perfectly natmal. It might almost be suggested, that the habit of 

 feeding so largely, as "Cuckoos do, on hairy cater])illars, whose 

 indigestible hairs form a fretwork in tlie gizzard, may also have its 



