IV PREFACE. 
together and properly digest all of the literature relating to this subject. This 
resulted in the projection of a critical review of the literature, begun in 1896 in the 
American Naturalist but left unfinished, owing to pressure of research work, and a 
card catalogue which is now here published in full with critical remarks. His 
third endeavor was to carefully work over, in the laboratory, field, and greenhouse, 
as opportunity offered, all of the so-called bacterial diseases of plants, submitting 
each supposed parasite to all of the tests of modern pathology. The latter has 
proved a far larger undertaking than was anticipated, the number of diseases 
attributed to bacteria having increased rapidly in recent years. It is expected that 
more than 125 diseases will be treated or touched upon in this monograph, many 
of which have come under the writer’s own observation. An attempt has been 
made to cover the literature of the whole world and to work over personally every 
disease so far as material could be obtained. 
The present volume contains an “outline of methods of work,” which was 
written up in substantially the same form four years ago, in connection with the 
investigations of the Laboratory of Plant Pathology, Bureau of Plant Industry, 
United States Department of Agriculture, its publication having been delayed in 
order to bring the rest of the manuscript into suitable shape. The monograph is 
published in this form with the approval of the Secretary of Agriculture. 
The bibliography at the end of this volume covers the general subject of 
bacteriology, exclusive of plant diseases, and is arranged chronologically by sub- 
jects. Not every good paper is referred to, but for the most part only such as 
have fallen under the writer’s own observation. It is believed, however, that by 
consulting these the student will soon be able to get hold of the entire literature of 
any special branch. ‘The reader who wishes to keep pace with the advance of the 
science should consult the International Catalogue (R) published by the Royal 
Society of London. 
The illustrations, especially those dealing with histology, have been drawn, 
with very few exceptions, under the direct personal supervision of the writer, every 
one of them when near completion having been inspected critically and modified 
in various details to correspond as closely as possible to the actual object. The 
slides from which the drawings have been made will be placed on file in the 
Laboratory of Plant Pathology, where they may be consulted. 
This monograph is not intended to take the place of ordinary text-books of 
bacteriology, of which there are now many, but rather to supplement the same, 
giving information where they are silent or misleading. It is hoped that it will 
be of value not only to plant pathologists, for whom it is primarily intended, but 
also to physicians and animal pathologists for purposes of comparison. In its 
preparation the writer has had also an eye to the service of gardeners, fruit-growers, 
and all who take an intelligent interest in plants. It is presented with a keen sense 
of its imperfections, but with the hope that it may at least serve its main purpose. 
While the writer has made every effort to be accurate in statement and just in 
criticism, it is too much to hope that he has always succeeded, and, therefore, he 
desires to crave pardon in advance for all errors of omission and commission, taking 
