Variations in Bacteria Caused by Change of Medium 5 



substances. The fact of loss of weight keeping pace with the age of 

 the culture may be interpreted to mean that the organism in an environ- 

 ment of abundant food may need more than the ordinary supply of 

 water, so that, the food decreasing, there is a decrease in the amount 

 of water absorbed. 



CULTURAL CHARACTERISTICS 



Since the characteristics of the organism as grown on its accustomed 

 medium are to be compared with those of a changed environment, 

 a summary of the present characteristics is necessary. In morphology, 

 staining, and cultural traits, this organism showed only what is 

 ordinary to B. Coli. On Hiss' carbohydrate-serum-water medium, 

 it produced acid and gas in dextrose, levulose, galactose, maltose, 

 saccharose, dextrin, and mannit. 



BIOCHEMICAL CONSTITUENTS 



Preliminary. The biochemical constituents are here understood 

 as Water and Volatile Matter; Ash and Ash Constituents; Sulphur; 

 Phosphorus; Calcium; Total Nitrogen; Amino-Nitrogen ; Fats and 

 Waxes; Coagulable Protein; Soluble Protein; Carbohydrates; Cel- 

 lulose-like Substances; Residue. 



In making determinations of this nature on bacteria, some of the 

 well established methods are obviously inapplicable, and less well 

 recognized ones had to be adopted, e. g., extraction of fat. This 

 necessitated, in such cases, before all else a careful investigation of 

 the method. 



DISCUSSION OF METHODS 



WATER AND VOLATILE MATTER were determined only by desiccation. 



ASH. The material was incinerated in a silica crucible and kept at 

 a dull red glow to constant weight; cooled in vacuo and weighed. 

 Constituents of Ash were subjected to ordinary qualitative and 

 quantitative methods. 



SULPHUR. Total Sulphur was estimated on both wet and dried 

 bacteria. The material was heated with sodium carbonate and an 

 excess of potassium nitrate, extracted with water, neutralized, and 

 after precipitation weighed as barium sulphate. 



