children. So he picks up stems of grass and water-weeds with his
mouth, and weaves them deftly into a compact nest as perfect as a
bird's, though some what different in shape and pattern, it rather
resembles a barrel, open at both ends, as though the bottom were
knocked out: this form is rendered necessary because the eggs, when
laid, have to be constantly aerated by passing a current of water
through the nest as I shall describe hereafter. No. 1 shows us such a
nest when completed, with the female stickleback loitering about
undecided as to whether or not she shall plunge and enter it. You
will observe that the fabric is woven round a fixed support of some
waving water-weeds; but the cunning little architect does not trust in
this matter to his textile skill alone; he cements the straws and
other materials together with a gummy mortar of mucous threads
secreted for the purpose by his internal organs.

[Illustration: NO. 2. FEMALE STICKLEBACK LAYING EGGS IN NEST.]

As soon as the building operations are fully completed, the eager
little householder sallies forth into his pond or brook in search of
a mate who will come and stock his neatly-built home for him. At this
stage of the proceedings, his wedding-garment becomes even more
brilliant and glancing than ever; he gleams in silver and changeful
gems; when he finds his lady-love, he dances round her, "mad with
excitement," as Darwin well phrased it, looking his handsomest and
best with his lustrous colours glistening like an opal. If she will
listen to his suit, he grows wild with delight, and coaxes her into
the nest with most affectionate endearments. In No. 2, as you
perceive, the mate of his choice has been induced to enter, and is
laying her eggs in the dainty home his care has provided for her. The
father fish, meanwhile dances and capers around, in a _pas de