35 



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

 young cultures there was no smell; in old cultures there was a feeble 

 odor. 



Ps. steivai'tl ))ehaves on potato nuicli like I^i<. lujucuitlil. 



Potato cjdinders on which Pa. cainpestru and Pa. pliaHcoll have 

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

 were attacked. 



Coconut. 



This sul)stratum was made ))y putting* clean, washed slices of coco- 

 nut Hesh into sterile, cotton -plugged test tul)es, 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 grape sugar (reducing substance), but is rich in oil. With the 

 exception of rice it is the Avhitest 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. 



Px. liijaclutld grows on this substratum Avithout retardation. Cul- 

 tures at room temperatures of 20° to 26° C. usualh^ appeared in 36 to 

 48 hours, when 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 flftieth day the bright 

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

 enc}' to thicken the fluid or make it yellow, or to cover the su])merged 

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

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

 is notsticky except in old cultures, which sometimes string up slightl}^ 

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

 sticky, but it dissolved slowl}^ in water and then lifted up 1 cm. when 

 touched with the loop. 



The color of Px. Jiyacinthl on coconut is bright yellow. After 7 

 days' growth on coconut the organism was yellower than an e([ually 

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

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

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

 that of a corresponding tu})e of l^a. pliaaeoll. After 49 da3's the color 

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

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



After 50 days at room temperatures of 18° to 27° C. its color was 

 between Ridgway's lemon yellow and his gamboge yellow (VI-10 and 

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

 was between canary yellow (light cadmium) and chrome yellow (Ridg- 

 way, VI-8). 



