138 BACTERIA IN RELATION TO PLANT DISEASES. 



end of two months a thin yellow rim 5 mm. wide ; a thin yellow pellicle over the whole sur- 

 face, fluid moderately clouded, translucent, a bright yellow precipitate 1.5 cm. broad, and 

 no crystals visible ; fluid feebly fluorescent. At the end of another month the fluid in each 

 one of the seven tubes was turbid and the precipitate slowly increasing, it being then 1 7 mm. 

 wide and about 4 mm. deep; the liquid was slightly fluorescent, and plainly to strongly alka- 

 line to neutral litmus. It was not viscid. At the end of four months these cultures were 

 still living; they were distinctly fluorescent and not at all viscid ; all had a deep chrome yellow 

 rim, and all but one had more or less pellicle; pseudozoogloeae were present. Repeated in 

 1908 with similar results: On twenty-third day heavily clouded with specks of yellow on the 

 surface (floating islands), and a granular pale buff -yellow precipitate. On shaking, a great 

 number of small flocculent particles filled the fluid. 



On nutrient starch-jelly the addition of the following substances gave no increased 

 growth: Lactose, maltose, dextrin, mannit, glycerin. Cane-sugar and galactose, on the con- 

 trary, greatly stimulated growth. On the slant surface of the jelly containing the cane-sugar 

 there was a copious, smooth, wet-shining, buff-yellow, sirupy growth. On that containing 

 the galactose there was 100 times as much growth as on the jelly containing glycerin, and 

 nearly as much growth as on that containing the cane-sugar. 



Bad. stewarti did not grow in 80 peptonized beef-bouillon (sodium hydrate), but 

 clouded 40 bouillon the first day or the beginning of the second. Probably there was 

 some error in the former titration, as a repetition in 1908, using 35 bouillon, gave no growth, 

 nor would it grow in 30 peptone beef-bouillon when tested in 1912. The maximum toler- 

 ated dose of sodium hydrate in bouillon, therefore, is not known with certainty, but is, I 

 believe, under 30 of Fuller's scale. On the acid side +30 bouillon clouded the first day 

 and +60 is believed to have been clouded feebly after a time; growth also occurred in +80 

 bouillon (acid of beef -muscle) , in +64 tomato juice, +40 cabbage juice, and in potato broth 

 reinforced with malic acid from +30 to +45, as has been stated already. The range of 

 toleration, therefore, for alkalies and acids is greater on the part of this organism than on 

 the part of many related forms, e. g., Bad. hyacinthi. 



Salted bouillon. The organism will tolerate a considerable amount of sodium chloride, i. e., 

 nearly or quite as much as Bacillus coli. In 1909, in experiments with two strains (McCulloch and 

 Galloway), Bacterium stewarti grew promptly in +15 peptone bouillon containing 5 per cent c. p. 

 NaCl, and after a time in bouillon containing 8 per cent. The experiment was repeated in 1912 

 with similar results. There appeared, after a time, to be a trace of bottom growth, even in 10 per 

 cent salt bouillon, but this should be repeated. 



Cohn's solution. The organism did not grow in Cohn's solution when inoculated into it from 

 young fluid cultures. Repetitions in 1908 gave the same results. 



Fermi's solution. The organism grows feebly in Fermi's solution. 



Reduction of nitrates. Bad. stewarti has no action on potassium nitrate. It is not reduced in 

 bouillon, either with or without the presence of grape-sugar. The growth of Bad. stewarti in nitrate 

 bouillon was feeble in comparison with that made by Bad. hyacinthi or Bad. campestre. 



Aerobism. So far as tested Bad. stewarti is strictly aerobic. It produces no gas and does not 

 grow in the closed end of fermentation-tubes when free from air. It is able, however, to get along 

 on a relatively small amount of air, as shown by experiments in vacua, etc. 



In an atmosphere of nitrogen Bad. stewarti behaved on coconut cylinders the same as Bad. 

 hyacinthi. At the end of 15 days, when the seal was broken.there was no visible growth .although the 

 check-tubes showed a distinct yellow color in 48 hours and continued to develop typically. Expo- 

 sure to the nitrogen also caused distinct retardation of growth after the seal was broken, the yellow 

 slime being first visible on the fifth to the eighth day thereafter. In another test, using white-turnip 

 cylinders, there was no growth during the 15 days exposure, and none subsequently. The checks 

 grew promptly. In a third experiment the absorption of the oxygen by the pyrogallol was very 

 slow, occupying 5 days. During this time there was some growth, but at the end of 15 days it was 

 paler yellow and only about one-thirtieth as abundant as in the check-tubes. 



In an atmosphere of hydrogen for 16 days there was either no growth or only a trace of growth, 

 according to the medium used : 



