LATE FELLOW OF CHRIST'S COLLEGE, CAMBRIDGE; PROFESSOR OF BOTANY AT THE ע stee, tran SD 565 APR 5046 PREFACE. THE following attempt at a popular exposition of a subject almost unknown in this country, originated in a series of short articles in Nature, and when the publishers proposed that I should add to these and cast them into the form of a book, I assented with the more pleasure because it afforded an opportunity of calling attention to several points well worth further investigation. Had my primary object been to write a treatise on the whole subject of the diseases of trees, I should have adopted a somewhat different plan, and discussed many of the phenomena at greater length. Chapter IV. will perhaps be regarded as too technical for the general reader, but it seemed |