Variations in Bacteria Caused by Change of Medium 13 



BIOLOGICAL VARIATIONS 



As the chemical constituents of the bacterial cell seem to be affected 

 by a change in medium, so does it appear that the biological character- 

 istics alter. Having seen that bacteria vary as stated above in regard 

 to chemical composition when grown on different media, it seemed 

 desirable to determine if such variation was accompanied (as might 

 be reasonably expected) by variations in the biological activities of 

 the organism. 



From those biological characteristics that can be definitely measured, 

 we have selected (i) the ability to produce enzymes capable of split- 

 ting different carbohydrates with the formation of gas and acid ; and 

 (2) the ability to agglutinate with immune rabbit serum prepared 

 with the organism as antigen. 



CARBOHYDRATES 



The organism (B. Coli) was grown on the eight different media 

 used above, and after about 200 generations were transplanted directly 



TABLE v 



Results of B. Coli grown on eight different media and 

 transferred to litmus-carbohydrate-serum-water 



'A ' indicates hours required to produce marked acidity to litmus. 

 1 G* indicates hours required for first appearance of gas. 



