Survival of the fit, [52].

Symphædra, [22].

Tabula rasa, [27], [24].

Tegetmeier, W. B., [34].

Teleological principles, [10], [16], [25].

Theories, nature of, [5] et seq.

Turbellaria, [28].

Units, vital, biological, physiological, etc., [8], [40], [41], [53], [56], [65], [80].

Useful modifications, value of initial stages of, [80]-[82].

Utility, [11], [18], [33], [45], [48], [62], [63], [82].