Spitz-dog crossed with fox, [268].
Sports in plants, [9].
Sprengel, C. C, on crossing, [98].
——, on ray-florets, [145].
Squirrels, gradations in structure, [180].
Staffordshire, heath, changes in, [71].
Stag-beetles, fighting, [88].
Sterility from changed conditions of life, [9].
—— of hybrids, [246].
—— ——, laws of, [255].