Hawk-moths, length of life of imago, [17].

Helicidae, length of life of, [55], [56], [57].

Heliotropism, [399].

Hemiptera, length of life of, [41].

Hens, length of life of, [36].

Hensen, on sexual reproduction, [282], [286];

on difference between germ-plasm and histogenetic nucleoplasm, [343];

on heredity, [369].

Heredity, [29], [71], [378];

defined, [72];