The period of Balfour's teaching included the momentous year 1860. The impulse of the new spirit introduced by Darwin did not stimulate Balfour as it might have done a younger man. His religious beliefs--always in evidence--were showing then the influence of his early environment, and whilst Darwin's work was incorporated in his teaching, the acceptance of Darwin's theory appeared too near the negation of faith. On Balfour indeed, as on others with like views, the immediate effect of the _Origin_ was the opposite of vivifying. It gave a shock. And this, I conceive, not so much a consequence of Darwin's own statement of his theory as of the forceful uncompromising attitude of the chief protagonist of his cause. Arrogance there was on the religious side, but no less also on the scientific side in the discussion. Perhaps it was well that the contest was sharp and bitter. It ended sooner, but its course was strewn with misconceptions and with confusion of cause and effect. In our days of complete reconciliation, when every tyro lisps in phyletic numbers as the outcome of Darwin's work, it is not amiss to recall the struggle at its inception--lest we forget. The system of Essays which formed so important a part of Graham's teaching remained as prominent and was even developed further in Balfour's course in a way which had the inestimable merit of making the student feel that his study of plants had a living relationship with the everyday concerns of life. Thus when Simpson was engaged in his epoch-making investigations on anaesthetics, the subject for an essay was the effect of anaesthetics on sensitive plants, and by way of emphasis, the prize awarded was a gift by Simpson himself. Similarly Balfour enlisted the sympathy of Messrs Lawson, the prominent agricultural nurserymen of the day, and their prizes for dissection of grasses, for kinds of cereals, and like subjects, were constant reminders of the relations of botanical study to agriculture. The subjects of essays covered a wide field. The titles--influence of narcotic and irritant gases, changes which have taken place in the Flora of Britain during the historical era, cytogenesis and cell development, phanerogamous embryology, cryptogamous reproduction, teratology--may serve to indicate this, and an essential was always the practical illustration, microscopic or other. For the use of the students Balfour compiled text-books which, like his lectures, are comprehensive in the field they cover, and encyclopaedic in the information they convey. His facile pen found expression too in numberless articles in encyclopaedias and magazines, and his activity as an expositor of botanical topics of the time was unbounded.