WILT-DISEASES OF TOBACCO. 



257 



The bacteria taken from one species of plant did not vary in media more than those taken from 

 another. Of 27 isolations of B. solanacearum (20 from tobacco, 2 from Acalypha boshmerioides, 1 from 

 Agcratitm conyzoides, 1 from Synedrella nodiflora, and 3 from Tectona grandis), all varied more or less 

 strongly. 



The retardation of growth due to sodium hydroxide is better shown in table 37. 



Table 37. Retarding Effect of Alkali on B. solanacearum by Days (Tests in Sets of 3). 



If one of the cultures succeeded, then from that others could be inoculated with a greater degree 

 of success, as shown by table 38. 



Table 38. Results of Further Studies of Sumatran Tobacco Organism in same Acid 

 and Alkaline Media {Always in Sets of 3 Tubes). 



Temperature and light are said to play no role in this variability. The test-tubes had been 

 cleaned with acetic acid, but some soaked in chromic-acid cleaning mixture ga\ r e the same result.* 

 With asparagin and potassium nitrate the results shown in table 39 were obtained. 



Table 39. Variable Behavior of Different Strains of Sumatran Tobacco Organism to Combinations of 

 Carbon and Nitrogen Foods (Tests always in Sets of 3 Tubes each). 



Further studies showed that media which failed to show growth when inoculated with small 

 doses of the bacteria would do so when inoculated with larger quantities, as shown in table 40. 



vSimilar results were obtained in neutral asparagin-glycocoll-KN0 3 , or urea solution, with glucose 

 or mannose, the heavier inoculation yielding the better results. 



When measured quantities of the bacteria were used the results shown in table 41 were obtained. 



*Medan III and Florida potato (1914) grew in Witte's peptone water + H 2 S0 4 (1 :ioooo), but not in the same 

 acidulated 1:1000 (3 days test at 27 C). 



