PREFACE.

A WORD in explanation of the history of these Lectures seems necessary. The substance of them formed a part of my course on Materia Medica and Therapeutics, at the St. George's School of Medicine, and of a course on the Vegetable Kingdom, in relation to the Life of Man, at the Royal Institution of Great Britain. The form they now assume depended on my appointment to the scientific superintendence of the Food Collection at the South Kensington Museum.

Feeling that our great public museums ought to be connected with oral teaching, in order that they might become the means of educating and elevating the people, I obtained the permission of the Committée of Council on Education to deliver courses of Lectures, for the purpose of supplying instruction in connection with the Food Collection. These Lectures were well attended, and I had every reason to be satisfied with their success. Under these circumstances, I agreed to a proposal of the Publisher of this volume to correct reports of them by a short-hand writer. The six first were thus published, when it was considered desirable that my public instructions at the Museum should be discontinued. As only a part of the Lectures had been delivered when their publication commenced, I was obliged to complete the