94 



ABSTRACTS 



In plating tests the Lipman and Brown agar proved to be the best 

 of the media studied, not only from colony counts, but in the variety 

 of organisms grown. This latter is judged from the macroscopic 

 appearance of the plates and by the fact that some organisms growing 

 on the Lipman and Brown agar would not live when transferred to 

 other media. 



The colonies on the sodium asparaginate agar were large, but in 

 only one of over fifty tests of organisms growing well on this media 

 did the organisms fail to grow on agar alone. 



The two best media were so different in constitution and the organ- 

 isms that grew best on them acted so differently when transferred from 

 one medium to the other that those ingredients furnishing carbon and 

 nitrogen were investigated further. These tests resulted in other 

 tests where 15 gms. of (best obtainable) agar-agar was the basis of all 

 the media. This was used both alone, and in combination with am- 

 monium nitrate, starch, Witte's peptone, sodium asparaginate, Liebig's 

 extract of beef; soil extracts, wheat straw extracts, and leaf extracts 

 were also used. 



The results of this work and of later work are shown in the follow- 

 ing table. The soil organisms reported on were chosen because of their 

 macroscopic differences. The known pathogens and known non-patho- 

 gens were the only known organisms studied. 



Media tests 

 (15 grams agar-agar is basis of all media.) 



Lipman plus Brown 



0.05 gram Witte Peptone 



2 grams St. plus 0.05 Peptone . . 

 H. J. Conn's media 



1 gram Na. asparaginate 



2 grams St. and 1 gram Na. asp 



Soil plus 1 gram NH4NO3 



Soil plus 1 gram Starch 



Soil plus 2 grams Starch 



1 gram NH4NO3 plus 1 gram 



Starch 



1 gram Starch 



2 grams Starch 



7 .5 grams Gelatine 



7.5 grams Gel. plus 1 gram Starch 

 7.5 grams Gel. plus 2 grams Starch 

 7.5 grams Gel. plus 2 grams Starch 



plus soil 



5 grams Liebi g' s Ext . plus 10 grams 



Peptone 



5 grams Liebig'sExt. plus 4 grams 



Starch 



24 son, 



ORGAN- 

 ISMS 



7 KNOWN PATHOGENS AND 8 KNOWN 

 NON-PATHOGENS 



Rank 3 days Rank 6 days Rank 8 days 



Patho- 

 gens 



12,13 



17 



10,11 



6 



16 



8 



15 



14 



10,11 



9 



5 



12,13 



7 

 4 



3 



Non- 

 Pathogens 



4« 



7 



16 



13 

 8, 9, 10 



14 

 8,9,10 



17 



15 

 8, 9, 10 



11 

 6 



12 

 5 



4 



Non- 

 Patho- 

 gens 



7 



16 



12 



8 



13,14 



9 



17 



15 



13,14 



11 

 5 



10 

 6 



4 



Patho- 

 gens 



11 



16 



9 



6 



14 



7, 8 



17 



13 



12 



10 



5 



15 



7,8 

 4 



Non- 

 Patho- 

 gens 



9 



16,17 



12, 13 



7 



14 



8 



16, 17 



15 



13 



10 

 5 



11 

 6 

 4 



