natural Hi/lory of the Cuckoo. 233 
clufter of enlarged eggs; but the mod forward of them was 
fcarcely larger than a milliard- feed. 
I would not be underflood, Sir, to advance that every egg 
which fwelis in the ovarium at the approach or commence- 
ment of the propagating leafon is brought to perfection ; but 
it appears clearly, that a bird, in obedience to the dictates of 
her own will, or to fome hidden caufe in the animal ceconomy, 
can either retard or bring forward her eggs. Befides the exam- 
ple of the common fowl above alluded to, many others occur. 
If you deflroy the nefl of a Blackbird, a Robin, or almoft any 
fmall bird, in the fpring, when fhe has laid her ufual number 
of eggs, it is well known to every one, who has paid any 
attention to enquiries of this kind, in how fhort a fpace of 
time fhe will produce a frefli fet. Now, had the bird been 
fnffered to have proceeded without interruption in her natural 
courfe, the egg s would have been hatched, and the young 
ones brought to a Bate capable of providing for themfelves, 
before (he would have been induced to make another nefl, and 
excited to produce another fet of eggs from the ovarium. If 
the bird had been deftroyed at the time fine was fitting on her 
fir ft laying of eggs, difleclion would have (hewn the ovarium 
containing; a great number in an enlarged Ante, and advancing: 
in the ufual progrefftve order. Hence it plainly appears, that 
birds can keep back or bring forward (under certain limita- 
tions) their eggs at any time during the feafon appointed for 
them to lay ; but the Cuckoo, not being fubje6t to the 
common interruptions, goes on laying from the time fhe 
begins, till the eve of her departure from this country : for 
although old Cuckoos in general take their leave the frfl week 
in July (and I never could fee one after the 5th day of that 
1 month *), 
