d hydrochloric acid, the first change
is the splitting off at (4) of the nitrogen in the form of ammonia and the
consequent conversion of the CN group into a COOH group, producing
amygdalinic acid. On further hydrolysis, this breaks up in the same order
as before. Similarly, it is possible to convert mandelo nitrile into
mandelic acid by splitting off the nitrogen to form a COOH group, instead
of splitting off the HCN group leaving benzaldehyde.

The mandelo nitrile glucoside contains an asymmetric carbon atom which is
wholly outside its glucose group, thus C_{6}H_{10}O_{5}-O-C_{6}H_{5}.CH.CN.
Hence, it may exist in dextro, levo, and racemic forms. In the amygdalin
molecule, it exists in the dextro form, which has been named "prunasin."
The levo form, known as "sambunigrin," has been obtained by hydrolysis
of a compound isomeric with amygdalin, whose composition has not been
definitely worked out; while the racemic form, known as "prulaurasin,"
has been prepared from isoamygdalin, by the action of alkalies. Hence,
all the possible compounds indicated by the presence of the asymmetric
carbon have been found and identified.

The crude enzyme preparation which is obtained from almond seeds, known as
"emulsin," contains two enzymes, _amygdalase_, which breaks the amygdalin
molecule at linkage (1), and _prunase_, which breaks it at (2). The action
of amygdalase must always precede that of prunase. In other words, it is
never possible to break off a disaccharide sugar from the molecule, either
by the action of prunase alone, or by means of any other hydrolytic agent.

=Dhurrin=, C_{14}H_{17}O_{7}N, is another glucoside of fairly general
occurrence in plants, which yields HCN as one of the products of its
hydrolysis. It is found in the leaves and stems of several species of
millets and sorghums. Frequent cases of poisoning of cattle from eating of
these plants as forage have been reported. On hydrolysis, dhurrin first
yields glucose and paraoxy-mandelo nitrile; the latter then breaks down
into paraoxy-benzaldehyde and HCN.

=Vicianin=, C_{19}H_{25}O_{10}N, is a cyanophoric glucoside, found in the
seeds of wild vetch, etc. On hydrolysis, it yields glucose, arabinose, and
_d_-mandelo nitrile. It is, therefore, similar to amygdalin, except that
one glucose molecule is replaced by arabinose.

THE MUSTARD OIL GLUCOSIDES

The seeds of several species of plants of the Cruciferae or mustard family
contai