"In Florida, in the spring when the mating instinct is strong, I have seen a flock of s ing about the sky, going through various intricate movements, with the precision of dancers in a ball-room . No sign, no signal, no guidance whatever. Let a body of men try it under the same conditions, and behold the confusion, and the tumbling over one another! At one moment the birds would wheel so as to bring their backs in shadow, and then would flash out the white of their breasts and under parts. It was like the opening and shutting of a giant hand, or the alternate rapid darkening and brightening of the sail of a tacking ice-boat. This is the spirit of the flock."