Malthusian principle, [65], [67].

Markings, butterflies', [16] et seq.

Maxwell, [4], [5].

Mean of variation, [78]-[79].

Meristic, [18].

Mimicry, [19], [51] et seq.

Minot, S., [54] footnote.

Models, mental, [4] et seq.

Molecules, [58].

Morgan, Prof. C. Lloyd, [32], [71], [83].