250 



BACTERIA IN RELATION TO PLANT DISEASES. 



SOURCES OF NITROGEN AND CARBON. 



As a stock solution for these tests, Honing used Meyer's mineral solution.* All the substances 

 tested were from Merck, and those marked "insoluble in water" were dissolved with as little as 

 possible of Na 2 CO 3 or HC1. 



In this stock solution, adding one substance as source of both nitrogen and carbon, the results 

 given in table 29 were obtained with the Deli tobacco bacteria. 



The one substance that brought out distinct differences in the isolations was asparagin. All 

 three cultures of Tg and Th showed growth and also one of Td. The rest remained entirely clear, 

 even after 14 days. 



For reasons given, the auxanographic method could not be used at Medan; the inoculations, 

 therefore, were all made into solutions after steam-heating to 100 C. on 5 consecutive days. 



Potassium Nitrate. With i per cent potassium nitrate (in the following solution : KH2PO 4 , o. i per 

 cent ; MgSO 4 , 0.03 per cent ; and NaCl, 0.5, alkaline) Uyeda found B. nicotianae made no development, 

 not even on addition of i per cent glucose or i per cent glycerin, while B. solanacearum gave a weak 



TABLE 29. Ability of Deli Tobacco Organism in Meyer's Mineral Solution to obtain both Carbon 



and Nitrogen from One Substance. 



growth in presence of the glucose and a normal one in the presence of the glycerin. This is wholly 

 in agreement with the Deli isolations of B. solanacearum with potassium nitrate in glucose and does 

 not show that Uyeda had two kinds of bacteria, since 4 of Honing's strains failed to grow like Uyeda's 

 B. nicotianae, while several others grew like B. solanacearum. In addition to these differences, Honing 

 found a strain which grew well with potassium nitrate and inuline, while another would not grow. 

 In the same way one strain grew with potassium nitrate and dextrine, while another would not grow ; 

 also one strain grew with potassium nitrate and sorbit, while another would not grow ; and, finally, one 

 strain grew with potassium nitrate and saccharose, while another would not grow. These facts, 

 Honing thinks, should make one very careful in drawing conclusions from a small number of cultures 

 made from a few strains. 



Potassium Nitrite. This substance may also serve as food. 



A sparagin. Uyeda's B. solanacearum did not grow with asparagin, while his B. nicotianae made a 

 feeble growth. That the latter, which with asparagin alone made a weak growth, made none what- 

 ever when i per cent glucose was added, should have indicated to Uyeda that bacteria are variable 



Water, 1,000.00; KHtPO 4 , i.oo; CaCl, o.io; MgSO 4 +7H,O, 0.30; NaCl, o.io; 



