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. hyacinthi. On the thirty-fifth day there was no increased 

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

 the bright yellow growth Avas 3 or ^ times as abundant and was now 

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

 stance, liberated b}^ the intruding organism. There was no visible 

 diastasic action except in the starch immediatel}^ 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 500 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 tAventy-third day, when 

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

 but there was no visible diastasic action. 



Ps. jphaseoli was A^ery pale and made a much less abundant growth 

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

 solution minus the glycerin) than it did on potato, or than did 7^-. cam- 

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

 grew rather better than Ps. cmnpestrls. 



Hyacinth Starch Jelly. 



This was made by adding 1 gram of dry sugar-free hj^acinth starchy 

 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 w^ere steamed 2 hours on each of 3 consecutive 

 daA^s at 91° C, this Ioav temperature being obtained by putting the 

 tubes in the top of the steamer Avith the Agents left open. The tubes 

 Avere inoculated Avith I^s. hyacinthi yqyy copiousl}- in the same manner 

 soon after the third steaming from a starch jelly culture T days old. 

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

 from 15° to 26° C. 



Pesult. — At the end of -IS hours (temperature, 21° to 22° C.) groAvth 

 Avas Adsible in each tube. At the end of the fourth day the 2 check 

 tubes Avere alike, the Avhole surface of the long slant l)eing covered 

 with a very thin, distinctly yelloAv groAvth. There Avas, hoAvever, no 

 visible diastasic action, the organism behaving on hj^acinth starch 

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

 sugar there was 1 or 5 times as much growth as in either of the check 

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

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

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

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



