Variations in Bacteria Caused by Change of Medium 



The media employed for obtaining growth and representing change 

 of environment are described in the adjoined table. 



TABLE II 



MEDIA EMPLOYED IN OBTAINING NINE DAYS* GROWTH OF B. COLI 



FOR ANALYSES 

 SOLID MEDIA: VEHICLE, AGAR 2. PER CENT 



I. Peptone, I. per cent 



II. Peptone, 0.5 percent 



III. Peptone, 0.25 per cent 



IV. Peptone, 0.25 per cent 



V. Peptone, 0.25 per cent 



VI. Peptone, 0.25 per cent 

 VII. Peptone, 0.25 per cent 

 VIII. Peptone, none 



Meat extract, i.o per cent 

 Edestin, 0.5 per cent 

 Flour proteins, i.o per cent 

 Meat extract, i.o per cent; Glu- 

 cose, i.o per cent 

 Meat extract, I .o per cent ; Glu- 

 cose, i.o per cent. ; Glycerol, 

 i.o per cent 



Butter soap, i.o per cent 

 Butter soap, i.o per cent 

 Potato juice, from whole un- 

 skinned potato, freed from 

 starch ; 500 grams potato to 

 litre of medium 



Titration 

 Neutral 

 Alkaline 

 Alkaline 



Neutral 



Neutral 



Bacteria collected from these several media constitute the material 

 for analyses by the methods already indicated, the number of deter- 

 minations in each analysis varying from 7 for ash to 20 for nitrogen. 

 For the sake of brevity three of the most variant results are indicated in 

 Table III. 



Since Table III does not include the results of all determinations, 

 but only the most variant, for the purpose of comparison the average 

 result for each series of determinations is therefore appended. Table 

 IV presents variations in almost all bacterial constituents. Though 

 strict interpretation of these results must necessarily await the light 

 of further research, attention must be directed to the fact that from 

 the simplest to the complex constituent variation is evident. The 

 water content varies, which may not be as significant as other varia- 

 tions. There is an increase in the amount of ash and amino-nitrogen 

 in the case of fat-media; protein is high where protein is present in the 

 medium, and highest where the medium-protein is in soluble form. 



