64 BACTERIA IN RELATION TO PLANT DISEASES. 



From these results it is probable that the organism can obtain its nitrogen from aspa- 

 ragin and ammonium salts but not from KNO 3 , and that it can use cane-sugar, dextrose and 

 glycerin ( ?) as carbon foods. Greig Smith says glycerin can not be utilized by the organ- 

 ism. Further experiments should be made. 



Greig Smith makes the following deductions from experiments made to test the influence 

 of salts upon the growth of the organism : 



(i) The bacterium has a preference for phosphate and is indifferent to the other acid radicals; (2) 

 the acid potassium phosphate, on account of its acidity, checked the growth; (3) potassium may be 

 replaced by calcium, magnesium, or ammonium; (4) sodium is a distinct poison. The medium used 

 was a faintly acid one containing 0.5 per cent peptone, 10 per cent dextrose, 2 per cent agar, and 2.5 

 per cent of the various salts to be tested. 



Greig Smith's conclusions regarding the influence of carbon foods are as follows : 



Either dextrose, levulose or saccharose are absolutely necessary for the free growth of the organ- 

 ism and the production of gum. The bacteria did not grow in the presence of the other sugars and 

 carbonaceous matters (glycerin,* starch, dextrin, maltose,* lactose*), from which we infer that these 

 cannot be utilized. Of the three sugars, levulose and saccharose are more easily assimilated than 

 dextrose. 



The medium was a faintly acid one containing 0.5 per cent peptone, 0.2 percent sodium 

 phosphate, 0.5 per cent potassium chloride, 2 per cent agar, and 5 per cent of the various 

 carbon substances. 



Cohn's solution: I can not find that we made any tests in Cohn's solution. 



Greig Smith states that he obtained a faint indol reaction in nutrient bouillon. 



So far as tested Bacterium vascularum is a strict aerobe (EFS., RGS.) . No gas is formed 

 in any of the common culture media, nor is there any clouding of the closed end of fermenta- 

 tion-tubes containing grape-sugar, cane-sugar, milk-sugar, maltose, mannit, or glycerin in i 

 per cent quantities in water containing 2 per cent Witte's peptone, although all were moder- 

 ately clouded in the open end and outer part of the U . Cultures were repeated in i per cent 

 peptone-water containing i per cent maltose and the same with i per cent mannit, but with 

 the same results. In twice-distilled water containing 2 per cent glycerin, i per cent dex- 

 trose, and i per cent sodium asparaginate there was no growth. This medium was alkaline 

 to litmus paper. 



The organism did not grow on steamed potato or in peptonized beef-bouillon in an 

 atmosphere of carbon dioxide (14 days) . One test only. The check tubes behaved properly . 



The thermal death-point lies between 49 and 50 C. when exposures are made from 

 young bouillon cultures as described in vol. I of this monograph. It is a little higher when 

 made from potato cultures. 



Growth is inhibited by a temperature of 37.5 C. (RGS., EFS.), and a temperature of 

 35 C. much retards it. Two out of three tubes of bouillon continued to be thinly clouded 

 after 27 days at 35 C. and were living, as shown by streak cultures on agar, but the streaks 

 developed colony-wise at first, indicating that the bouillon was then thinly stocked with 

 living organisms. Bouillon-tubes inoculated copiously and placed at 37.5 C. for 7 days 

 not only remained clear but refused to cloud when subsequently placed at room tempera- 

 tures (i 2 days) . Agar plates poured from these three tubes also remained free from colonies. 

 The three check-tubes clouded promptly. 



There is more rapid growth at 30 C. than at room- temperature (18 to 23 C.), about 3 

 times as much in the first 48 hours, but at the end of 4 days not much cloudier than the checks. 



*That strain of Bacterium vascularum with which I have experimented has moderately clouded peptone-water 

 containing glycerin, maltose, and lactose, but in the light of Greig Smith's statements I am not prepared to say that it 

 would not have clouded the peptone-water to the same extent without these substances. Additional tests should be 

 made. I can not make them myself, because I have lost all my cultures of this organism. 



