* * *

These types of oxidation effects now established give a definite
significance to the physiological functions of the peroxide, which is a
form of 'active oxygen' of extremely wide distribution. It would have
been difficult _a priori_ to devise an oxidant without sensible action
on aldehydic groups, yet delivering a powerful attack on hydrocarbon
rings; or to have suggested a synthesis of the sugars from tartaric acid
with a powerful oxidising treatment as the first and essential stage in
the transformation.

Our present knowledge of such actions and effects suggests a number of
new clues to genetic relationships of carbon compounds within the plant.
The conclusion is certainly justified that the origin of the pentoses is
referable to oxidations of the hexoses, in which this form of 'active
oxygen' plays an important part.

We must note here the researches of O. Ruff, who has applied these
oxidations with important results in the systematic investigation of the
carbohydrates.

UEBER DIE VERWANDLUNG DER _D_-GLUCONSAeURE IN _D_-ARABINOSE (Berl. Ber.,
1898, 1573).

~CONVERSION OF _D_-GLUCONIC ACID INTO _D_-ARABINOSE.~

* * * * *

_D_ UND _L_ ARABINOSE (_Ibid._ 1899, 550).

* * * * *

ZUR KENNTNISS DER OXYGLUCONSAeURE (_Ibid._ 1899, 2269).

~ON OXYGLUCONIC ACID.~

Ruff in these researches has realised a simple and direct transition
from the hexoses to the pentoses. By oxidising gluconic acid with the
peroxide the beta --CHOH-- group is converted into carbonyl at the same
time that the terminal COOH [alpha] is oxidised to CO_{2}. The yields of
the resulting pentose are large. Simultaneously there is formed an
oxygluconic acid, which appears to be a ketonic acid of formula
--CH_{2}OH.CO.(CHOH)_{3}.COOH--.

From these results we see a further range of physiological
probabilities; and with the concurrent actions of oxygen in the forms of
or related to hydrogen peroxide on the one side, and ozone on the other,
we are able to account in a simple way for the relationships of the
'furfuroid' group, which may include a number of intermediate terms in
the hexose-pentose series.

Following in this direction of development of the subject is a study of
the action of persulphuric acid upon furfural.

EINWIRKUNG DES CARO'SCHEN REAGENS AUF FURFURAL.

C. F. CROSS, E. J. BEVAN, and J. F. BRIGGS (Berl. Ber., 1900, 3132).

Regarding this