FOSTERERS OF THE CUCKOO 197 
yet shown a series of eggs by one Cuckoo taken from 
nests of Chaffinch, Greenfinch, Willow Wren, etc. ; 
and it is at least possible that with such species are 
lacking the conditions necessary to the establish- 
ment of a race of Cuckoos persistently duping 
them . 
It is probable that the modus operandi of the 
Cuckoo in egg-deposition is in the case of at least 
all ground-nesting species similar to that I have so 
often described with Pipits. Our investigations 
have shown that it was not merely the habit of 
one individual Cuckoo to lay when sitting on the 
Pipit’s nest, but the action of the several Cuckoos 
which came under our observation. But there is 
no doubt that many Cuckoos do not lay in the 
nests of their dupes, since their eggs have been 
taken from nests in holes to which it would have 
been impossible for the parasites to have obtained 
access for the purpose of laying. Where the 
Cuckoo cannot lay in the nest of the destined 
fosterer it must still remain a matter of pleasant if 
unprofitable speculation as to what she does. 
Having laid her egg, it is believed that she transfers 
it in her bill to the chosen receptacle. There has 
been much controversy over the Cuckoo’s exact 
method of carrying her egg. Some writers, such 
