Ideals and culture, [186]

Indian speculation, [269]

Individuality of animals, [49], [50], [51], [52], [55]

Infallibility, [123], [236]

Inspiration, [246], [247], [253], [254]

Instincts, [154]

Intellect, [243]

Intermediate and linear types, [87]

International Scientific Series, [173]

Invertebrata, Manual of, [175]