1896.] The Bacterial Diseases of Plants. 635 
would be a great advantage, and the quality of the work would 
more than correspondingly improve. Only in some such way 
can the strong tendency toward trashy publication be elimi- 
nated and light and order evolved from the present chaos. 
With few exceptions, vegetable pathology seems to have been 
specially unfortunate in the class of persons who have devoted 
themselves to the study of bacterial diseases. While the 
bacterial side of animal pathology has had its Pasteur and 
Koch, its Esmarch, Hueppe, Fliigge, Gaftky, Frænkel, Pfeiffer, 
Leffler, Duclaux, Metchnikoff, Chamberland, Roux, Welch, 
Sternberg, Smith, Prudden, and a host of other skilled exper- 
imenters, scarcely less eminent, and has made correspondingly 
great progress, the study of the bacterial diseases of plants has 
been principally in the hands of botanists without special 
laboratory training in bacteriology and even destitute in some 
cases of an elementary knowledge of right methods of work. 
The great development of modern bacteriology is attributable 
largely to the discovery that human diseases are due to these 
organisms, and to its consequent alliance with medicine, but 
there is no reason why the same rigid scrutiny of methods and 
sharp calling in question of statements which have led tosuch 
brilliant results in animal pathology in recent years should 
not be applied in the same way to vegetable pathology. Accur- 
ate experimentation and trustworthy results are from a purely 
scientific standpoint quite as desirable in one field as in the 
other. 
_ Two things are especially to be kept in mind in describing 
any bacterial disease of plants: (1) The pathogenesis must be 
worked out conclusively; (2) If the organism is named, it must 
be so described that it can be identified by any competent bac- 
teriologist no matter where it is found. 
The four requirements under the first head, i. e. strates dang ic 
are now generally recognized to be as follows: 
_ A. Constant association of the germ with the disease. 
B. Isolation of the germ from the diseased tissues and study 
of the same in pure cultures on various media. 
_ C. Production of the characteristic symptoms of tbe disease 
by inoculations from pure cultures. 
