Medical students, [181], [279]

Medusæ, [33], [39], [40], [41], [42], [96], [123]

Membrane bones, [134]

Mental capacity of apes, [152]

Mercy, [265]

Mertens, [56]

Mesohippus, [77]

Metals, transmutation of, [257]

Metaphysics, [241]

Metaphysics and science, [217]