FERMENTABLE SUBSTANCES 79 



is then chipped in the shell with a sterile needle and the 

 inoculation made through this. The hole is afterwards 

 closed with a little sterilised wool and collodion. 



Uschinsky's Fluid Parts. Pasteur's Fluid. Parts. 



Sodium chloride . . 5-7 Cane sugar .... 10 



Calcium chloride . . 0-1 Tartrate of ammonia . . 1 



Magnesium sulphate . 0-2-0-4 The ash of 1 grm. of yeast. 



Di-potassium phosphate . 2-2-5 Water .... 100 



Ammonium lactate . . 67 



Sodium asparaginate . 3-4 



Glycerine . . . 30-40 



Water .... 1,000 



Uschinsky's fluid is a solution of known composition without 

 protein which can be used for investigating the chemical products 

 of bacteria. Pathogenic organisms grow well in it and produce 

 their toxins. 



Pasteur's fluid is a good culture medium for yeasts, etc l 



Fermentation media. Fermentation reactions obtained 

 with various fermentable substances, such as sugars, 

 alcohols and glucosides, are of considerable value in the 

 differentiation of organisms. The changes brought about 

 by growth are an acid or an alkaline reaction, or the former 

 changing into the latter, or acid formation with gas pro- 

 duction. 



The substances chiefly employed for fermentation reactions 

 are : 



Alcohols: Glycerol (glycerin), mannitol, dulcitol, adonitol, 

 inositol, sorbitol, erythntol (all, except glycerol, frequently written 

 with the termination -ite, instead of -itol). 



Sugars. Monosaccharides (incapable of yielding other sugars 

 by hydrolysis). Pentoses (C 5 . . .) : Arabinose, xylose, rhamnose. 

 Hexoses (C 6 . . .) : Glucose (dextrose), fructose (Isevulose), 

 galactose, mannose. 



Disaccharides (yielding two other sugars by hydrolysis : 

 Ci 2 . . .) : Lactose, maltose, sucrose (saccharose, cane-sugar). 



1 Several formulae for synthesised media will be found in the Journal of 

 Experimental Medicine, vol. iii, p. 666. 



