“In the spring a fuller crimson comes upon the robin’s breast;
    In the spring the wanton lapwing gets himself another crest;
    In the spring a livelier iris changes on the burnish’d dove;
    In the spring a young man’s fancy lightly turns to thoughts of love.”

Not to be out of the fashion, therefore, the romantic stickleback does precisely the same thing as all these distinguished and poetical compeers.  And he does it for the same reason, too; because he wants to get himself an appropriate partner.  “There is a great deal of human nature in man,” it has been said:  I am always inclined to add, “And there is a great deal of human nature in plants and animals.”  The more we know of our dumb relations, the more closely do we realize the kinship between us.  Fish in the spring are like young men at a fair—­all eager for the attention of their prospective partners.

[Illustration:  NO. 1.  FEMALE STICKLEBACK ABOUT TO ENTER NEST.]

The first care of the male stickleback, when he has acquired his courting suit, is to build a suitable home for his future wives and 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 triomphe at the success of his endeavors.