38 A SOFT ROT OF THE CALLA LILY. 



tube. The amount of growth was only moderate. The Uschinsky's 

 solution showed no growth at this time. In twenty-four hours the 

 tubes of Uschinsky's solution were still clear, but at the end of forty- 

 eight hours after exposure to the air the solution was distinctly 

 clouded, showing that free oxygen is necessary for the growth of the 

 calla organism in Uschinsky's solution. 



In the nitrate bouillon there was only a moderate amount of growth 

 at the time the jar was opened, but the solution was distinctly clouded. 

 There was a white precipitate 7 mm. in breadth, but no pellicle or rim 

 had formed. The nitrates were reduced to nitrites, as shown by the 

 usual test. The common bouillon was distinctly and iniiforml}' clouded. 

 Apparentl}^ the growth had been twice as rapid as in the nitrate bouil- 

 lon, as indicated by the degree of cloudiness of the tubes and by the 

 large amount of white precipitate, which w^as fully twice as abundant 

 jis in the nitrate bouillon tubes. No rim or pellicle formed in any of 

 the tabes. 



EFFECT OF HYDROGEN, 



Tubes of slant agar, Uschinskj^'s solution, ordinary bouillon, and 

 nitrate bouillon were inoculated with the calla organism and placed in 

 a hydrogen atmosphere. The hydrogen was generated b}^ the action 

 of dilute sulphuric acid upon zinc. The gas thus produced was 

 passed through solutions of silver nitrate, potassium permanganate, 

 sodium hydrate, and distilled water into a chamber containing the 

 inoculated tubes. The chamber was filled and exhausted six times, 

 thus insuring practically a pure atmosphere of hj^drogen. The cham- 

 ber was then sealed and left undisturbed for twenty days, at the end 

 of which time the following results were noted: 



The organism had made a feeble growth on the slant agar, as indi- 

 cated b}^ a very faint streak along the surface of the medium, and a 

 small amount of whitish precipitate to the depth of 2 mm. had been 

 deposited in the angle between the agar and the side of the tube. 

 Uschinskv's solution was feebl}^ clouded throughout. A small amount 

 of deposit to the breadth of 7 to 8 mm. had formed in the bottom of 

 the tube. The ordinary bouillon was feel^ly clouded throughout and 

 a white precipitate 8 mm. in breadth had been deposited. The nitrate 

 bouillon was feebly clouded, with a small amount of white deposit 12 

 mm. broad in the bottom of the tube. No rim or pellicle had formed 

 in an}^ of the fluids. 



COMPARISON OF CALLA-ROT GERM WITH SIMILAR ORGANISMS. 



Bacillus carotovorm Jones." — Upon comparing the calla organism 

 with the carrot-rot germ, as described by Jones, it is found to differ in 



"Jonep, L. R. A Soft Rot of Carrot and Other Vegetables Caused l)y Bacillus 

 Carotovorus, Jones. Thirteenth Annual Report of the Vermont Experiment Station, 

 1900, p. 299. 



