64 



(the product of a spore which passed through the sterilizing oven 

 uninjured) had come to the surface, and I suspected that sugar liberated 

 by this colony had diffused through the substratum and stimulated the 

 growth of Ps. hyacinihi. On the thirty -fifth da}^ there was no increased 

 growth and no visible diastasic action in jelly No. 2, but in jelly No. 1 

 the bright 3^ellow growth was 3 or 4 times as abundant and was now 

 clearly attributable to diffusion of sugar, or some other assimilable sub- 

 stance, liberated by the intruding organism. There was no visible 

 diastasic action except in the starch immediately around where this 

 white colony had come to the surface. The effect of the growth of 

 this intruder was most clear cut and interesting. 



For comparison with these two tubes a culture was laid at the same 

 time on starch jelly No. 2 with addition of 50U milligrams of dextrin. 

 The organism grew well on this substratum, making 4 to 6 times as 

 much growth as in the check tubes. On the twenty-third day, when 

 last examined, there was an excellent growth and had been for 3 weeks, 

 but there was no visible diastasic action. 



J*s, jphaseoli was very pale and made a much less abundant growth 

 on nutrient starch jelly No. 2 (made with the modified Uschinsky's 

 solution minus the glycerin) than it did on potato, or than did Pi<. cmn- 

 pestris. In Uschinsky's solution, on the contrary, it was yellower and 

 grew rather better than Ps. campestris. 



Hyacinth Starch Jelly. 



This was made by adding 1 gram of dry sugar-free hyacinth starch, 

 obtained from bulbs, to .5 c. c. portions of Uschinsky's solution. Three 

 tubes were prepared, to one of which was added 500 milligrams of 

 cane sugar. The tubes were steamed 2 hours on each of 3 consecutive 

 days at 91° C, this low temperature being obtained by putting the 

 tubes in the top of the steamer with the vents left open. The tubes 

 were inoculated with Ps. hyacinth/ very copiously in the same manner 

 soon after the third steaming from a starch jell}" culture 7 days old. 

 They were kept together in a dark place at room temperatures ranging 

 from 15° to 26° C. 



Result. — At the end of 48 hours (temperature, 21° to 22° C.) growth 

 was visible in each tube. At the end of the fourth daj'^ the 2 check 

 tubes were alike, the whole surface of the long slant being covered 

 with a very thin, distinctly yellow growth. There was, however, no 

 visible diastasic action, the organism behaving on hyacinth starch 

 exactly as on potato starch. In the tube which received the cane 

 sugar there was 4 or 5 times as much growth as in either of the check 

 tubes. This growth was bright yellow and covered nearly the whole 

 surface of the slant, but there was no visible diastasic action, the 

 increased growth being due to the presence of the cane sugar. A lit- 

 tle later this tube was accidentally broken.. The check tubes were 



