198 :<>; T Biological Chemistry. 



CH 2 (OH)-(CH(OH)) 3 C CH: N-NH C,H 5 + 2HC1 + 2H 2 

 N 



= 2C 6 H 5 NH-NH 2 -HC1 



+ CH 2 (OH) CH(OH) CH(OH)CH(OH) CO CHO 

 The osone obtained from dextrose or Isevulose, on treatment 

 with nascent hydrogen, is reduced to laevulose 



CH 2 (OH)-CH(OH) CH(OH) CH(OH) CO CH20H 

 By means of a series of reactions it is therefore possible 

 to convert dextrose into laevulose. With phenylhydrazine 

 it yields the osazone (which is identical with the osazone 

 obtained from laevulose). This substance on hydrolysis 

 yields the osone, from which, on reduction with nascent 

 hydrogen, laevulose is obtained. 



The General Characters of the Sugars. In addition to 

 glucose and laevulose, a large number of other substances 

 are included amongst the monosaccharoses. Since the 

 recognition of the chemical constitution of the former, it 

 has been possible to define this class chemically. Under 

 the above designation may be included a series of sub- 

 stances, of which some are found native and others are 

 artificial laboratory products. All are characterized by the 

 fact that they contain, in addition to an aldehyde or 

 ketone radicle, one or more hydroxyl radicles. Mono- 

 saccharoses are known containing from two up to nine 

 carbon atoms, and are according to the number classified as 

 bioses, trioses, tetroses, etc. The simplest member of the 

 class of monosaccharoses is glycollic aldehyde 



CH 2 OH 



CHO 



As an example of a triose may be mentioned glycer- 

 aldehyde and the isomeric ketone, dihydroxy acetone, of 

 which the formulae are given below 



