596 S. H. AYERS, C. S. MUDGE AND PHILIP RUPP 



SUMMARY AND CONCLUSIONS 



1. The standard extract medium with washed agar showed 

 in many cases, when market milk was examined, a much higher 

 count than the same medium with regular shred agar. 



2. Washing agar reduced its content of calcium and magnesium 

 salts. 



3. A few experiments indicated that the removal of these 

 salts was a factor in the cause of the higher counts. This point, 

 however, is merely suggested by the results and not definitely 

 proved. 



4. Since certain samples of milk show a higher count when 

 plated on a washed-agar standard extract medium than on the 

 regular standard extract medium, it seems evident that washing 

 removes something detrimental to the growth of certain species 

 of bacteria. This naturally suggests that a further study is 

 needed of the value of washed agar in lines of bacteriological 

 work where it has not been used. 



