158 



()tiii':k Steciks i!Ki,().\(iiN(; id iiii.s (iuonr*. 



The followiiiti;- species also Ix^lon^ to this o-i-oup and appear to he 

 distinct from the foregoing, but our knowdedge of their cultural char- 

 acters is more or less imperfect: 



(1) y^y. juglatidiK Pierce. Parasitic on the young nuts, leaves, and 

 stems of Juglans raij'ia in C-alifornia. The cause of an economically 

 serious disease in walnuts. Reseml)les I\. ('(iirqjedrls. Pierce does 

 not mention having attempted to inoculate his organism into cruciferous 

 plants, l)ut the writer has tried the reverse of this without success, 

 viz, inoculations of /-!s-. campestrl^i and 7\ j^hast'oll into young rapidly 

 growing shoots of the walnut (-/. r(^(ji<(). 



(2) P.H. vdsvularxuii (Cobb). Parasitic on sugai' cane in Australia 

 and elsewhere. The vascular l)undles are filled with a yellow slime, 

 the canes are dwarfed, and the sugar content is reduced. 



(3) Pf<. diiudld (Arthur and Bolley). Isolated from carnations 

 (Dianthus spp.), and supposed to be the cause of a spot disease. Com- 

 mon on the surface of carnation leaves, but now believed to be purely 

 saprophytic. 



(4) Pa. amardnti n. sp. Occurs on species of Amarantus (weeds in 

 tields) in the Eastern United States, tilling and l)rowning the vascular 

 bundles and hollowing out the tissues in, their vicinity into closed cavi- 

 ties tilled with this organism. The plants which are attacked ai'e 

 stunted, droop, and dry up without any visible cause. The organism 

 is a short rod and when grown on culture media has more orange in 

 its pigment than any others here described. On the whole, it seems 

 to ])e most nearly related to Ps. f<tevmrti 



(f)) Ps. iiKjlvacearum n. sp. Parasitic on cotton (Gossypium spj).). 

 This organism causes the very characteristic leaf disease known as 

 Atkinson's angulai' leaf -spot, and also a water-soaked spreading spot- 

 disease of the capsules comi)arable to that produced on walnuts by 

 Ps. jugJandls 'M\(\. on bean pods l»y Ps. 2)h<(><eoN. This bacterium has 

 nearly the same thermal death point as Ps. cduipestrf's and much 

 resembles it in many othei- ways, but its slime is more ti'anslucent on 

 potato, and it is not parasitic to cab])age. The writer has had this 

 organism under observation for several years, and has successfully 

 inoculated it into young cotton ])olls and leaves. Tissues of the cot- 

 ton plant which are not growing rapidly do not readily contract the 

 disease. 'I'his yellow organism is not the same as the green tluorescent 

 gei-m isolated })y Stinlman from rotting cotton capsules and named 

 BaclJhis (jimypina. A full account of the cotton disease is in 

 preparation. 



21788— No. 2S— 01 11 



O 



