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 



