66 



PHYSIOLOGY 



of glucose, which are thus rendered possible, are represented by the following structural 



formulae : 



H C OH 



OH C H 



or 



HCOH 



CH,OH 



HCOH 

 I 

 CH 2 OH 



In these molecules the OH attached to tbe end group can be replaced by other radicals, 

 including other sugar molecules. In this way we get the formation of glucosides. Thus, 

 if glucose be dissolved in methyl alcohol and be treated with hydrochloric acid, we 

 obtain a and ft methyl glucosides, the formulae of which would be represented as follows : 



H 0-OCH 3 CH 3 C H 



r 



HCOH 



I \ Q I 



HOCH / u HOCH 



HCOH 



I 

 CH 2 OH 



Instead of methyl we might insert other groups, and even other hexose groups, such 

 as glucose or galactose, obtaining the two sugars maltose and lactose, which may thus 

 be regarded as glucosides maltose as the a-glucoside of glucose, lactose as the /3-galac- 

 toside of glucose. The mode of combination of the two hexose groups to form these 

 disaccharides may be represented as follows : 



H H OH H H 

 CH 2 OH C C C C C glucose rest 

 OH V HOH 







HO H HO HO 



OHC C C C C CH 2 glucose rest 

 H OH H H 



O 



maltose. 



H OH II 



CH 2 OH C C C C -C galactose rest 

 OH H H OH 



HO H HO HO 



OHC C C C C CH 2 glucose rest 

 H OH H H 



lactose 



