868 PREMATURE NESTLING. 
by song, for though winter songs seem to be 
continued into spring and at last appear to resolve 
themselves into the pure vernal notes of exhilar- 
ation and enjoyment, I trust it has been sufficiently 
shewn that song is far from being any test of 
the incubating processes; so that prematurely 
induced song even in those species not accus- 
tomed to chaunt during winter is not an evidence 
of prematurely induced love, the two questions 
of song and love being in short distinct and worthy 
of separate investigation, though the two circum- 
stances in song-birds are for awhile naturally 
connected and coincident. 
That food is capable of inducing precocity of love, 
and consequent incubation in domesticated birds, 
we have proofs in the common fowl and duck, which 
are frequently known to lay through the winter. It 
is also known that Canaries will even commence 
building in cages so early (or rather date) as 
November, but though there can be no question 
that food is in these instances the main stimulus, 
and furnishes sufficient bodily powers for these 
offices, I believe it has been remarked that mild and 
fine winters greatly influence the proceeding, con- 
tributing as I think, to induce the irregularity. 
That food is not the sole reason, would appear by 
those exceptions to the rule of the fowl and duck 
laying in winter, during severity of season, and by 
the instances I shall presently name of wild birds 
being influenced in their nestling-period by circum- 
stances of weather. And by the same rule it appears 
that weather cannot be the only influence, because 
these same two species in their wild state are never 
known to nestle and incubate before the usual vernal 
season observed by the generality of birds; but it © 
will be noticed that Robins occasionally build at 
Christmas on the occurrence of unusually fine mild 
weather. I haye myself seen a nest with eggs of 
