BY

H. MARSHALL WARD, Sc.D., F.R.S.

FELLOW OF SIDNEY SUSSEX COLLEGE, HONORARY FELLOW OF CHRIST'S COLLEGE
AND PROFESSOR OF BOTANY IN THE UNIVERSITY OF CAMBRIDGE

PRESIDENT OF THE BRITISH MYCOLOGICAL SOCIETY, AND FELLOW OF THE
LINNEAN AND ROYAL HORTICULTURAL SOCIETIES; HONORARY FELLOW
OF THE MANCHESTER LITERARY AND PHILOSOPHICAL SOCIETY
AND OF THE BOTANICAL SOCIETY OF EDINBURGH

London

MACMILLAN AND CO., Limited

NEW YORK: THE MACMILLAN COMPANY

1901

All rights Reserved