on adaptation, [300];
on medium of heredity, [318], [355].
Najadae, length of life of, [56].
Natica heros, length of life of, [56].
Nautilus, persistence of, [300].
Nematodes, polar bodies of, [188];
nuclear division of ovum of, [234], [368].
Neuroptera, length of life of, [40].
Neuroterus, length of life of summer generation, [49];
of winter generation, [50].