96 



able extent. On the contrary, within a fewdays growth was enor- 

 mously .stimulated. If the volume of growth of 7's. hy<ichitki on the 

 17 per cent cane-sugar agar at the end of eight days be reckoned as 1, 

 then that of Ps. campestr'iH was 2 or 3 and that of Ph. phaseoli was 3 or 

 4. On the 23 per cent cane-sugar agar, on the fourth day, the growth 

 of Ps. campestris was five times as much as in the check tube, and that 

 of i^s. phiseoli -'vastly better." On the twelfth day the cultures of 

 Ps. campestris and Ps. jjhaseoll resembled each other closely in color, 

 general appearance, and amount of growth, which latter was ten 

 times that in the corresponding tube of Ps. hyacinthl. On the thirty- 

 sixth day the slime of Ps. pluiseoU consisted of rods. doul)lets, fours, 

 and many chains 50 to 120 }x long. 



(7) The growth of Ps. cainpesfris and Ps. jyhaseoli on the sugar agars 

 was smooth, wet-shining, and often abundant enough and thin enough 

 to flow like thick sirup on tilting the tubes. That of Ps. hyacinthi 

 would never flow and was distinctly areolated, reticulated, wrinkled, 

 or shagreened, as already described. 



Sodium Acetatk. 



The stock (1:95) containing this substance was compounded as fol- 

 lows : 



Distilled water, 400 c. c. 

 Dipotassium phosphate, 0.800 gram. 

 Magnesium sulphate, 0.0-40 gram. 

 Ammonium phosphate, 0.040 gram. 

 Sodium acetate, 2 grams. 



This medium was filled into cotton-plugged test tubes and sterilized 

 in the usual way. It was inoculated with Ps. hyacinthi x^vy copiously 

 from a young culture on coconut. It was under observation 5 weeks 

 at 25° to 30° C, but growth progressed very slowly and was never 

 anything more than feeble. At the end of the 5 weeks the fluid 

 was still feebly clouded and there was no rim of germs or pellicle, 

 but in the fluid on the wall of the tube were several hundred small, 

 ragged, whitish flocks and on the bottom there was a pale yellow pre- 

 cipitate 5 mm. wide. The growth was not better than in Uschinsky's 

 solution. 



Ps. campestris 'also grew feebly in this fluid, and Ps. stcwarti would 

 not grow at all (only one test). 



NUTRIENT STARCH JELLY WITH SUGARS, GUMS, AND ALCOHOLS. 



Some comparative tests of these four yellow organisms as to color, 

 rate of growth, etc., were made in tubes of slant nutrient, starch jelly 

 to which 500 milligrams of special kinds of carbon foods were added — 

 e. g., dextrin, lactose, maltose, etc. The growth in these tubes was 

 compared with that in tubes of starch jelly to which the sugars, etc., 

 were not added. My general conclusions are as follows: 



