THE third volume of Dr. E. F. Smith's work on “Bacteria in Relation to Plant Diseases” deals exclusively with “vascular diseases”—that is, those in which the causal organism advances along the vascular tissues of the plant, completely blocking up the zylem vessels. When compared with the account by Russell under the same title, written in 1892, the present work shows markedly the immense progress made since that date in this branch of botanical study. It is a compilation representing indefatigable labour, and forms, with the preceding volumes, a comprehensive summary of all that is known under the head of bacterial diseases of plants. A feature of the work is the care taken to collect a complete biblography, and the author's extraordinarily wide knowledge of the subject and the extent of his own observations and research render his critical review of all investigations bearing upon the etiology of the disease of extreme value to other workers in this field. Mor6over, the full abstracting of original papers, which are brought quite up to date, and lengthy excerpts concerning methods, technique, and results, fulfil the purpose of enabling the reader to form his own conclusions and emphasise the essential character of the publication as a book of reference.