32 



Ps. campestris, and Ps. phaseoli looked much alike, but the hyacinth 

 germ was the brightest yellow and the cabbage germ the palest. On 

 the seventeenth day Ps. hyadnthi was also noted as brighter yellow 

 than the others. In another series of cultures the slime of Ps. hyadn- 

 thi was distinctly yellower on the sixteenth day than that of Ps. cam- 

 pestris^ Ps. phaseoli., or Ps. stevxirti. On the forty-seyenth day the 

 color of Ps. hyacinthh was saffron yellow (Ridgway, VI-4). The color 

 of each of the other three organisms was paler, lying between buff 

 yellow and chrome yellow. The cultures of these three organisms 

 were also alkaline to litmus on yarious dates, and in cultures of the 

 same age the slime on the seyenteenth and forty-seyenth day was more 

 strongly alkaline than that of Ps. hyacinthl. All said, however, the 

 cultures of all four of these organisms were much alike on this 

 substratum at all stages of growth. 



(3) Poured plates of Ps. hyacinthh were made in Petri dishes, using 

 one of Mr. M. B. Waite's standard (litmus) neutral agars, in which 

 Bacillus amylovorus had been found to make a good growth. In yery 

 crowded plates containing 8,000 to 10,000 colonies per field (Zeiss 16 

 mm. and 12 ocular), the agar, at room temperatures (25'' C), became 

 milky cloudy on the fourth day. There were no distinct surface colo- 

 nies, and the buried ones were irregular in outline, i. e., with ragged 

 margins like the colonies of Ps. campestris. In a plate of the same 

 age, but containing onl}^ about 600 buried colonies in each field (16 

 mm. 12 ocular), the colonies were larger, but otherwise of much the 

 same character, i. e., roundish or somewhat irregular in shape with 

 rough margins. No distinctly fusiform colonies were to be seen. 

 Fusiform buried colonies were, however, observed in plate cultures 

 made from Mr. Dorsett's agar. 



In thin sowings of Ps. j)haseoli on nutrient agar in Petri dishes 

 (25 surface colonies and about 10 buried ones), on the seventh day 

 (25"^ C), the surface colonies were pale yellow, smooth, wet-shining, 

 not piled up, and had thin, distinct margins. The}^ Avere 1.5 to 1 

 mm. in diameter. The buried colonies were elliptical or bluntly 

 pointed (0.6 to 0.7 b}^ 0.3 to 0.1 mm.). The margin of the buried 

 colonies was distinct but frequently a little roughened under the 

 Zeiss aplanat. On the eleventh day some of the buried colonies 

 were breaking through to the surface. The entirely buried ones 

 were still small and elliptical, with either pointed or rounded ends. 

 They were yellow in color and their margins were more or less rough- 

 ened by small blunt projections. The surface colonies were now 3 to 

 8 mm. in diameter, smooth and wet-shining. Buried in the colon}^ 

 were a number of lighter and darker rings. The color was distinctly 

 yellow, but pale rather than bright, i. e., somewhat like straw j-ellow. 

 The margins were thin and well defined. Under high magnifications 

 zoogloeae were visible in the colonies. There was nothing j^^culiar \\\ 



