THE FUNGI WHICH CAUSE PLANT DISEASE 19 



Cells spirally curved or represent- 

 ing part of a spiral, division in 



one direction III. Spiiillaces. 



Cells cylindric in sheathed threads. . . IV. Chlamydobacteriaces. 



Cells with sulphur Order II. Thiobacteriales. 



Motile rods in pseudoplasmodial masses 

 in a gelatinous matrix, and forming 

 highly developed cysts Order III. Myzobacteriales. 



The species of families 3 and 4 and of orders II and III, some 

 twenty-five genera in all, are so far as is known, unimportant as 

 regards plant disease. All of the known plant pathogens belong 

 to one or other of the first two families of the Eubacteriales. Each 

 of these families contains several dangerous parasites upon ani- 

 mals, e. g., Bacillus typhosus, Spirillum cholerae-asiaticae, Bacte- 

 rium tuberculosis. 



The specific characters of bacteria are chiefly chemical or 

 physiological and rest in the relation of the forms to oxygen, gel- 

 atine liquefaction, fermentation of various sugars, acid production, 

 relation to nitrogenous compounds, chromogenesis, etc. ■ ' 



To enable brief expression of these characters the Society of 

 American Bacteriologists endorses the following numerical sys- 

 tem.* 



A Numerical System of Recording the Salient Characters of an 

 Organism. (Group Number) 



100. Endospores produced 



200. Endospores not produced 



10. Aerobic (Strict) 



20. Facultative anaerobic 



30. Anaerobic (Strict) 



1. Gelatine liquefied 



^ 2. Gelatine not liquefied 



0.1 Acid and gas from desctrose 



0.2 Acid without gas from dextrose 



0.3 No acid from dextrose 



0.4 No growth with dextrose 



* This will be found useful as a quick method of showing close relationships 

 inside the genus, but is not a sufficient characterization of any organism. 



