28 SCIENCE PROGRESS 



lactose or its stereoisomer z'so-lactose, while the other represents 

 that of melibiose, the disaccharide obtained by the partial 

 hydrolysis of raffinose. The first formula is the one assigned 

 to lactose for the following reasons. When lactose is methyl- 

 ated by means of methyl sulphate and sodium hydroxide, 

 eight methyl groups are introduced and heptamethyl methyl 

 lactoside results ; on hydrolysis this substance yields tetra- 

 methyl galactose and a trimethyl glucose whose constitution 

 proves to be represented by the formula : 



CH 2 .OCH 3 



CH.OH 

 r— CH 

 I CH.OCH 3 



CH.OCH 3 

 — CH . OH 



Theory permits of the existence of three other possible trimethyl 

 glucoses, but all these are excluded for various reasons and 

 the constitution of lactose is therefore definitely established. 

 It will be seen from formula i that lactose contains the group : 



\ /CH 2 . OH 



^>CH . O . CH<^ CH _ 



which is a hitherto unknown mode of linking of two sugar 

 molecules in the form of a branched chain ; this being so, there 

 need no longer be any reluctance in assuming that the reducing 

 group of one hexose may be united with a second residue 

 through any one of the hydroxyl groups of the latter. The 

 existence of a number of isomeric disaccharides is thereby 

 readily explained, as, for example, the four compounds maltose, 

 «so-maltose, gentiobiose, and cellobiose, all of which contain 

 two glucose residues. 



The constitution of another vegetable alkaloid has recently 

 been established by Hess and Eichel (Berichte, 191 7, 50, 1192). 

 The rind of the root of the pomegranate tree contains five 

 alkaloids, only one of which, -^-pelletierine, has hitherto been 

 investigated ; the main constituent, however, pelletierine, has 

 now been proved to be the aldehyde of coniine of the formula : 



CHax^xj tsjtt /CH . CH 2 . CH 2 . CHO 



