ly be capable of copying those sounds which fall
within that range. There is plenty of evidence to show that the power of
imitation is almost unlimited, at all events that it is not confined
within such narrow limits as are here demanded. Hence it seems clear
that the diversity of song is not to be sought in structure, but in some
innate capacity to play one tune in preference to another; and if this
be so, and if out of the same instrument, which has been primarily
evolved to further the biological end of intercommunication, all manner
of diverse sounds can be made to proceed, the problem of the origin of
song is to that extent simplified.

We must next inquire into the nature of song, and endeavour to ascertain
whether all the individuals of a species are alike proficient, or,
failing this, whether there is any quality which can be observed to be
constant under all conditions. I watch the Reed-Buntings in a marsh and
find that there are three males occupying adjoining territories. Two of
them are fully mature and their plumage is bright: that is to say the
crown is black, the collar and breast are white, the flanks are dull
white spotted with black, and the mantle is reddish-brown. The third is
immature: the crown, instead of being black, is suffused with brown; the
collar, instead of being white, is mottled with brown; and the flanks
are more heavily streaked with brown. These three birds take up their
positions in February, and, as is their wont, sing incessantly each day
at daybreak. The song of the first two is normal, including the usual
number of phrases which flow in no definite sequence, but are combined
and recombined in different order, and the tone is pure; that of the
third, the immature bird, is, however, very different; for just as in
comparison its plumage is dull, so the phrases of its song are limited
and reiterated with great monotony, the tone is impure, and the whole
performance is dull and to our ears unmusical. I watch them from
February to June, and observe the order in which they are mated--first a
mature male; next, after a short interval, the immature male; and
finally, after a still longer interval, the remaining bird gets a mate.
As the season advances, still keeping watch on the development of the
plumage and of the voice of the immature male, I observe that no very
definite change takes place--that the colours remain dull, that there is
a conspicuous absence in the song of certain phrases,