Although « vast amount of research haa been;
done In the field of carbohydrate chemistry,
comparatively little attention has been given to the
group of substances which may bo classified under
the heading of acid polysaccharides. In this group
we find such substances as occtins, plant gums,
hemioelluloees, mucilages, soluble spoolflc substances
produced by bacteria, and alginic acid from algae.
Moat of these substances appear to be formed by the
modification of cellulose under the influence of
enzymes, few, if any of them, being produced directly
by photosynthesis. Acid 'polysaccharides apparently
play a very important, though poorly understood,
role in natural orocesses.