,109 



peraturo 8.2^ C), there had been some further growth. On June 4, 9 

 a. m. (temperature 8.5° C), there was a distinct increase of growth 

 over what was present 24 hours earlier. One of the two tubes was 

 now removed to room temperatures of 25° to 26° C. During the next 

 2(5 hours the growth in this tube doul)led. During the same period 

 there was a slight growth in the other tube (temperature 8.5° C). 

 At this time, in this tube, a bright yellow growth covered more than 

 1 sq. cm. of the surface where 5 days before (after the shaking) no 

 growth whatever was visible. All of this growth took place ]>etween 

 7.4- and 9° C, the temperature most of the time during the 5 days 

 ranging between 7.5° and 8.5° C. 



(4) Four tubes of strongly alkaline beef broth (stock 382 neutral to 

 phenolphthalein) were each inoculated with a 3 mm. loop from a well- 

 clouded beef broth culture 3 days old. One of these tubes was held 

 at room temperatures of 20° to 25° C. This culture was moderately 

 clouded on the third day and passed through a normal growth. The 

 other 3 tubes were placed in the ice chest for 18 days at 2.8° to 4.5° C. 

 (mostly 3° to 4° C), during the whole of which time they remained 

 perfectly clear. On then removing them to room temperatures they 

 clouded in 16 hours at 21°-23° C. The rapidity with which they 

 clouded when removed from the ice box suggests that the bacteria 

 grew slightly at times while exposed to the low temperature. 



The mininumi temperature of Ps. campestris is not known. It lies 

 below 7° C. The minimum temperature of Ps. steioartl is not known 

 exactly, but it is believed to be a degree or two higher than that of 

 Ps. hyacinthi for the following reason: Tubes of Ps. stewartl were 

 exposed in the ice l)ox at 2.8° to 4.5° C, along with those of the 

 hyacinth germ. There was no clouding in 18 days, and on removing 

 to room tempcrtitures the tubes were not clouded until the third or 

 fourth day, and then only feebly. The check tubes clouded on the 

 second and third days. The fluids used were Uschinsky's solution and 

 an alkaline l)eef broth (stock 382). Each tube was inoculated with 

 one 3-millimeter loop from a young fluid culture (3 days old). The 

 date of clouding on removal indicates clearly that, contrary to the case 

 of Ps. hijaelnthi^ there had >)een no growth whatever during the 18 

 da3^s' sojourn of the tubes in the ice chest. 



FORMATION OF ACIDS. 



With exception of the production of a small amount of acid from 

 ethyl alcohol (probably acetic acid), the formation of acids t)y Ps. 

 hyacinthi is rather oliscure, in spite of all the attention I have given 

 to it. At times, especially when small cpiantities of the carbohydrate 

 were used, no acid was detected from the growth of this organism in 

 the presence of sugars. Even when large quantities of the various 

 sugars were used there was no promj)t change from alkaline or neutral 



