43 



standing in distilled water, i. e., by its feeble action on starch; and 

 (4) its pathogenic properties. Other distinctions are given in Bulle- 

 tin No. 28. Readily distinguished from Ps. siewarti by (1) its differ- 

 ent, brighter color; (2) its feeble growth in Ilschinsky's solution; (3) 

 its liquefaction of gelatin and Loeffler's blood serum; (4) its lower 

 thermal death point; (5) its lab ferment; (6) its much greater sensi- 

 tiveness to acids ; (7) its more luxuriant growth on turnip and rutabaga. 



From facts in possession of the writer it is certain that there are 

 many yellow organisms moi-e or less closely related to the four men- 

 tioned in this paper, i. e., nonsporiferous, rod-shaj)ed, micro-organ- 

 isms, multiplying by fission, possessing one polar flagellura, and 

 capable of living parasitically or semiparasitically upon various 

 plants. All of these parasitic yellow organisms, at least all I have 

 examined, are morphologically quite different from Bacillus coU, 

 Bacillus amijlovorus, Bacillus tracheiphilus, or any other micro- 

 organism having flagella distributed over its whole surface. They 

 also differ in many cultural peculiarities. They are, however, related 

 to each other in many ways, and appear to form a natural group. I 

 have an idea also that in some species the production of the brown 

 pigment, and in others the production of the yellow pigment, has 

 been nearly or quite extinguished. The species in which both pig- 

 ments come the nearest to being equally well developed is, perhaps, 

 Fs. cainpestris. The yellow pigment appears to be a lipochrome. 

 (See Bui. 28.) 



There are also, I believe, many morphologically similar yellow 

 bacteria which are purely saprophytic. 



