32 SECTIONAL ADDRESSES 
Nature in 1925. The experimental work of the succeeding two years 
made it possible, with the aid of colleagues and pupils, to establish the 
broad generalisation that all normal sugars higher in the series than tetroses 
are constructed on the basis of the six-atom skeleton model which can 
cee ce cee os ese caus eee 
Skeleton Model of Glucose. Model of B-Glucose. 
be regarded now as the unit of the complex carbohydrates such as cellu- 
lose, starch, and many others. ‘This simple model assumes the character 
of a sugar as soon as it is clothed with hydrogen atoms and hydroxyl 
groups. 
This generalisation, published in 1927, had presented itself as a strong 
probability from the moment it was seen that the representative sugar 
occurring in nature, glucose, conformed to this structural type. The 
experimental basis for the whole of the preliminary work was strengthened 
and supported by the systematic study of the sugar lactones carried out 
between the years 1924 and 1927. In the latter year there appeared a 
paper on the formulation of normal and y-sugars as derivatives of pyran 
and furan, and the suggestion of a new nomenclature. The normal 
sugar types can all be given a standard structure recognisable under the 
name of a pyranose. ‘The labile or y-sugars, which had hitherto been but 
little investigated, were shown to be ascribable to the parent form of furan 
and therefore recognisable under a nomenclature describing them as 
a furanose type. The developments of this nomenclature were there- 
after simple, inasmuch as the spatial arrangement of hydroxyl groups 
and hydrogen atoms, which characterised structurally identical forms, 
could be made abundantly clear by the addition of the characteristic 
prefix defining the kind of configuration which differentiates one sugar ~ 
of any class. ‘This nomenclature has been generally adopted and with 
the advantageous result that much confusion has been banished from the 
literature. ‘Thus arabinose assumes two structural forms represented by 
the terms arabopyranose and arabofuranose and, similarly for the other 
pentoses, xylose, ribose and lyxose. The corresponding forms for glucose 
are represented by the expressions glucopyranose, glucofuranose and 
similarly mannopyranose and mannofuranose, and so on for all aldo- 
hexoses and also for the keto forms fructopyranose and fructofuranose. 
This scheme of nomenclature would only have academic interest if it con- 
