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Journal of Agricultural Research 
Vol. XXV, No. 12 
In beef infusion media with a P H value of 5.5 the soybean organisms 
produced no growth and the clover organisms did not grow until after 
three to five days and then only slightly. From the delayed and slight 
amount of growth, it is assumed that in beef infusion a P H value of 5.5 
represents about the limit of acid toleration. 
Growth records made on third and fifth days after inoculation show 
that for all these organisms P H values 6.4 to 6.7, in either beef infusion 
or beef extract media, were most favorable for production of early and 
continued growth. 
temperature relations 
The organism grows well at a wide range of temperature. In one 
series of trials at Madison on this phase of the problem cultures on 
potato-agar slants and in bouillon were incubated at temperatures 
ranging from 3 0 to 39 0 C. at 3 0 intervals. In another, temperatures of 
25°, 3 °°> 3i°> 33°> 34°, 35°> 37°, and 38° C. were maintained. The 
parasite was able to make appreciable growth at 3 0 C. Its optimum in 
bouillon was 26°, whereas in agar 18 0 to 21 0 C. appeared to be most 
favorable. Slow but continued growth could be maintained at 34 0 C., 
but 35 0 inhibited development. 
In determining the thermal death point in studies at Madison, two 
loopfuls of 48-hour-old broth culture were transferred to tubes of beef- 
extract-peptone broth. After 10-minute exposures in the usual man¬ 
ner the tubes were cooled and incubated. As a result of two series 
of trials, it was determined that the thermal death point lies between 48° 
and 49 0 C. 
Experiments at Washington with the Virginia strains gave results 
entirely in agreement with these statements. 
resistance to desiccation 
Vigorous broth cultures, 48 hours old, were diluted with water to 
twice the orginal volume, and drops of this suspension were allowed to 
dry on sterile cover glasses kept in sterile Petri dishes. After the drops 
had dried, tests were made by inserting the cover glasses into tubes 
of nutrient broth. No growth appeared after 30 minutes’ desiccation, 
so that the organism is to be regarded as very susceptible to drying. 
Tests in Washington with the Virginia strains gave the same results. 
vitality on culture media 
The clover organism has been found to retain a vitality on the usual 
culture media for an indefinite period, having been maintained in Wiscon¬ 
sin on potato agar without appreciable loss of vigor for about four years. 
PATHOGENICITY 
The type organism from red clover in Wisconsin has been found to 
hold its pathogenicity in agar culture for about one year but has tended 
gradually to lose it thereafter. The strains from the other localities 
have behaved similarly. The preliminary pathogenicity trials made at 
Madison, Wis., in 1916 included inoculations of red clover and soybeans, 
since it was then thought that the bacterial leafspot and soybean blight 
