28 THE FUNGI WHICH CAUSE PLANT DISEASE 



1-2 X 0.5 ^, with rounded ends, actively motile by one long polar 

 flagellum. Bright chrome-yellow in growth; disastatic ferment 

 present. No gas; aerobic. It was isolated from diseased nuts, 

 leaves, and twigs of English walnut in California in 1901. In- 

 oculations by spraying demonstrated its pathogenicity. The 

 organism is closely related to Ps. campestris but is distinguished 

 from it by the abundant bright yellow pigment produced upon the 

 surface of extracts of leaves of walnut, magnolia, fig, castor bean 

 and loquat. 



Ps. leguminiperdus (v. Oven.) Stev.,*^ said to be distinct 

 from Ps. phaseoii, occurs on peas and other legumes. It was 

 isolated, cultivated and inoculations made. 



Ps. levistici Osterw.** occurs on Levisticum. 



Ps. maculicolum (McC.) Stev. (Group number 211.3332023.) 

 A short rod, forming long chains in some media. Ends rounded. 

 Size from leaf 1.5 to 2.4 n by 0.8 to 0.9 n; in 24-hour beef-agar 

 culture, 1.5 to 3 ju by 0.9 /x. No spores, actively motile, one to 

 five polar flagella two to three times the length of the rod. Mo- 

 tile in most artificial media. Involution forms in alkaline beef 

 bouillon. Pseudo-zoogloeae in Uschinsky's solution. Gram nega^ 

 tive. Stains readily with carbol fuchsin and Avith an alcoholic 

 solution of gentian violet. 



Agar plate colonies visible on the second day as tiny white 

 specks, in three to four days, 1 to 3 nmi. in diameter, white, 

 round, smooth, flat, shining, and translucent, edges entire, with 

 age dull to dirty white, shghtly irregular, edges undulate, slightly 

 crinkled, and with indistinct radiating marginal lines. Buried 

 colonies small, lens-shaped. 



Agar streak cultures white, mar^ns slightly imdulate. Beef 

 bouillon clouds in twenty-four hours. Growth best at surface 

 where a white layer, not a true pellicle, is formed. No zoogloese. 

 No rim. 



Gelatine stab cultures liquefied in eight to ten dajrs. Growth 

 from surface crateriform; slight, white, granular precipitate. Slight 

 green fluorescence. No separation into curd and whey. Indol 

 production feeble. T. D. P. 46°. Opt. 24-25°. Max. 29°. Min. 

 below 0°. 



Isolated from cauliflower leaves on which it forms brownish to 



