35 



starch was also but little affected (see Feel)le diastasic action). In 

 3^oung- cultures there was no smell; in old cultures there was a feeble 

 odor. 



Ps. stevxirtl behaves on potato much like Fs. hyacintld. 



Potato c^dinders on which Ps. caiiipeHtrls and Ps. phaseoli have 

 grown are somewhat softened as if the middle lamella of the cell wall 

 were attacked. 



Coconut. 



This substratum was made by putting clean, washed slices of coco- 

 nut flesh into sterile, cotton-plugged test tubes, adding 1 or 2 c. c. of 

 distilled water (from a tin-lined copper tank), so as to cover the lower 

 one-third or one-half of the slice, and steaming 15 or 20 minutes on 3 

 consecutive days. The coconut flesh contains no starch and very 

 little grai^e sugar (reducing substance), but is rich in oil. With the 

 exception of rice it is the whitest culture medium known to the writer. 

 All the yellow germs which I have tried make a satisfactory growth on 

 this medium, and owing to its whiteness the contrast in color is very 

 striking. 



Ps. kyacinthi grows on this substratum without retardation. Cul- 

 tures at room temperatures of 20° to 25° C. usually appeared in 36 to 

 48 hours, Avhen not too sparingly inoculated, and made a good growth 

 in 3 or 4 days. Growth continues for several weeks and usually 

 becomes quite abundant (in one culture on the fiftieth day the bright 

 yellow slime was over 1 mm. deep), but the organism shows no tend- 

 ency to thicken the fluid or make it yellow, or to cover the submerged 

 parts, any more than on potato, and there is little precipitate. The 

 growth on this medium is smooth, wet-shining, and homogeneous. It 

 is not sticky except in old cultures, which sometimes string up slightly. 

 After 50 days in the ice chest the bacterial layer was not noticealdy 

 sticky, but it dissolved slowly in water and then lifted up 1 cm. when 

 touched with the loop. 



The color of Ps. Kyacinthi on coconut is bright yellow. After 7 

 da3's' growth on coconut the organism was yellower than an equally 

 good growth of the same age on turnip. At the end of the same 

 period it was decidedly yellower than a corresponding culture of Ps. 

 campestrls. After 7 days and 25 days its color was about the same as 

 that of a corresponding tube of Ps. phaseoli. After 49 days the color 

 differed, if at all, from the color of a corresponding tube of Ps. phaseoU 

 in being a trifle brighter, i. e., in containing less orange. 



After 50 days at I'oom temperatures of 18° to 27° C. its color was 

 between Ridgway's lemon yellow and his gaml)oge yellow (VI-10 and 

 11). After the same period in the ice chest, at 7° to 15° C, its color 

 was between canary yellow (light cadmium) and chronie yellow (Kidg- 

 way, VI-8). 



