racted with alcohol, the residue freed from alcohol
and subjected to acid hydrolysis.

The hydrolysed extract was neutralised and fermented. In the early
stages of growth the furfuroids were completely fermented, i.e.
disappeared in the fermentation. In the later stages this proportion
fell to 50 p.ct. In the earlier stages, moreover, the normal hexose
constituents of the permanent tissue were hydrolysed in large proportion
by the acid, whereas in the matured straw the hydrolysis is chiefly
confined to the furfuroids. In the early stages also the permanent
tissue yields an extract with relatively low cupric reduction, showing
that the carbohydrates are dissolved by the acid in a more complex
molecular condition.

These observations confirm the view that the furfuroids take origin in a
hexose-pentose series of transformations. The proportion of furfuroid
groups to total carbohydrates varies but little, viz. from 1/3 in the
early stages to a maximum of 1/4 at the flowering period. At this period
the differentiation of the groups begins to be marked.

Taking all the facts of (1) and (2), they are not inconsistent with the
hypothesis of an internal transformation of a hexose to a
pentose-monoformal. Such a change of position and function of oxygen
from OH to CO within the group --CH.OH-- is a species of internal
oxidation which reverses the reduction of formaldehyde groups in
synthesising to sugars, and appears therefore of probable occurrence.

These constitutional problems are followed up in (3) by the indirect
method of differentiating the relationships of these furfuroids to yeast
fermentation, from those of the pentoses. Straw and esparto celluloses
are subjected to the processes of acid hydrolysis, and the neutralised
extracts fermented. With high furfural numbers indicating that the
furfuroids are the chief constituents of the extract, there is an active
fermentation with production of alcohol. The cupric reduction falls in
greater ratio to the original (unfermented) than the furfural.
Observations on the pure pentoses--xylose and arabinose added to
dextrose solutions, and then exposed to yeast action--show that in a
vigorous fermentation not unduly prolonged the pentoses are unaffected,
but that they do come within the influence of the yeast-cell when the
latter is in a less vigorous condition, and when the hexoses are not
present in relatively large proportion.

(4) The observations on the growing plant were r