44 SECTIONAL ADDRESSES 
varied types of polysaccharides which Nature doubtless provides, chemists 
have only succeeded in isolating and characterising a comparatively small 
Arabo- 
furanose unit. 
Xylopyranose units. 
number. A great many of which we have at present no knowledge will 
doubtless be isolated from natural sources by the application of the more 
modern methods of investigation. It seems evident from the work of 
Raistrick and others, who have prepared complex polysaccharides in vitro 
by the action of moulds on nutrient solutions containing glucose and 
other sugars, that many similar synthetic processes must go on in the 
plant. The detailed investigation of several of these polysaccharides, 
obtained by the agency of micro-organisms, has served to increase our 
knowledge of the type and variety of modes of assembly of sugar units 
in the more complex carbohydrates. It was altogether unexpected, for 
example, that the growth of P. Charlesii on glucose would produce two 
polysaccharides, one composed only of mannose residues and the other 
only of galactose residues. The detailed structure of the former has now 
been investigated and the polysaccharide prepared in this way and known 
as mannocarolose has been shown in our recent work to have a chain length 
of 9-10 mannopyranose units united through the 1 : 6 positions as indicated 
here. 
{ 
| 
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L 
| 
i 
| 
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| 
M 
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1 
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| 16-7 
1 1 
Yields 2:3: 4 :6-tetramethyl- Yields 2 : 3 : 4-trimethylmannose (II) 
mannose (III). and methyl alcohol. 
Still more striking is the polysaccharide varianose obtained ina similar 
manner by the growth of P. varians in glucose which gives rise to a complex 
