94 BACTERIOLOGICAL AND ENZYME CHEMISTRY 



Six-carbon Sugars {aldohexoses) 



CHO OHO CHO OHO CHO 



I I I I I 



H— C— OH HO— C— H HO— C— H H— 0— OH H— C— OH 



I I I I I 



H— C— OH HO— C— H H— 0— OH HO— C— H HO— C— H 



I I I I I 



HO— C— H H— C— OH HO— G— H H— C— OH HO— 0— H 



I I I I I 



HO— C— H H— C— OH HO— C— H H— C— OH H— C— OH 



1 I I I I 



CHjOH CH2OH CH2OH CH2OH CH2OH 



Z-Mannose c^Mannose ^Glucose (i-G-lucose (2-Galactose 



The Di-saccharoses. — The chief members of this group are 

 cane sugar, milk sugar, and malt sugar. By the action of 

 dilute acids, or, as will be shown later, by the activity of certain 

 organisms or enzymes, they are converted into hexoses accord- 

 ing to the general equation 



C12H22O1X + H2O = CgHi20e -j- CgHijOg 



This splitting up of the di-hexose into two hexoses is 

 generally known as inversion, because in the case of cane sugar 

 which is dextro-rotatory, the resultant mixture of sugars 

 is Isevo-rotatory, owing to the fact that the laevo-rotatory 

 power of fructose or Isevulose is greater than the dextro- 

 rotatory power of glucose or dextrose. 



Cane sugar forms glucose and fructose, lactose forms 

 glucose and galactose, and maltose two molecules of glucose. 



The following are a few interesting 'facts in regard to the 

 three sugars above mentioned : — 



Cane Sugar. — Saccharose or sucrose occurs in large quan- 

 tities in the sugar cane and in beetroot, from which two 

 sources the world derives practically the whole of its sugar. 

 Both in the case of sugar cane and beetroot, the general 

 methods of extraction are much the same. The material 



