e
lignocelluloses.

The actual production of furfural by boiling with condensing acids is a
quantitative measure of only a portion, i.e. certain members of the
group. The hydroxyfurfurals, not being volatile, are not measured in
this way. By secondary reactions they may yield some furfural, but as
they are highly reactive compounds, and most readily condensed, they are
for the most part converted into complex 'tarry' products. Hence we have
no means, as yet, of estimating those tissue constituents which yield
hydroxyfurfurals; also we have no measure of the furfurane-rings
existing performed in such a condensed complex as lignone. But, chemists
having added in the last few years a large number of facts and
well-defined probabilities, it is clear that the further investigation
of the furfuroid group will take its stand upon a much more adequate
basis than heretofore. On the view of 'furfural-yielding' being
co-extensive with 'pentose or pentosane,' not only were a number of
important facts obscured or misinterpreted, but there was a barrenness
of suggestion of genetic relationships. As the group has been widened
very much beyond these limits, it is clear that if any group term or
designation is to be retained that of 'furfuroid' is 'neutral' in
character, and equally applicable to saturated substances of such widely
divergent chemical character as pentoses, hexosones, glycuronic acid,
and perhaps, most important of all, levulose itself, all of which are
susceptible of condensation to furfural or furfurane derivatives, as
well as to those unsaturated compounds, constituents of plant tissues
which are already furfurane derivatives.

From the chemical point of view such terms are perhaps superfluous. But
physiological relationships have a significance of their own; and there
is a physiological or functional cohesion marking this group which
calls for recognition, at least for the time, and we therefore propose
to retain the term furfuroid.[1]

~General Experimental Methods.~--In the investigation of the cellulose
group it is clear that methods of ultimate hydrolysis are of first
importance. None are so convenient as those which are based on the
action of sulphuric acid, more or less concentrated (H_{2}SO_{4}.3H_{2}O
- H_{2}SO_{4}H_{2}O). Such methods have been frequently employed in the
investigations noted in this volume. We notice a common deficiency in
the interpretation of the results. It appears to be sufficient to