334 SCIENCE PROGRESS 



the a-compourd has the formula (C 6 H 10 O 5 ) 4 . When digested 

 with acetic anhydride and zinc chloride, the two dextrins are 

 not only acetylated but both apparently yield derivatives of half 

 the original molecular complexity, the hexasaccharide giving 

 a non-acetylated trisaccharide and the tetrasaccharide a 

 hexacetylated disaccharide. The corresponding " saccharides," 

 triamylose and diamy/ose, are obtained on displacing the acetyl 

 groups by hydrogen : both are crystalline. 



Taking into account the composition of the C 6 units — the 

 presence in each of only three hydroxyl groups and of OH 2 less 

 than in glucose — and the fact that both compounds are without 

 action on Fehling's solution and do not exhibit the phenomena 

 known as mutarotation, the following formula is a not improbable 

 representation of the disaccharide : 



■ o , 



CH . CH(OH) . CH . CH . CH(OH) . CH 2 (OH) 



o< >o 



CH.,(OH) . CH(OH) . CH . CH . CH(OH) . CH 



I : O ! 



It may be hoped that at no distant date, with the aid of data 

 such as the discovery under consideration affords and concep- 

 tions such as those introduced by Barlow and Pope, it will be 

 possible to arrive at a clear representation of the manner in which 

 the atoms are close-packed even in so complex a molecule as 

 that of starch. 



