is =amygdalin=.
Amygdalin was first discovered in 1830, and was one of the first substances
to be recognized as a glucoside. It is found in large quantities in bitter
almonds and in the kernels of apricots, peaches, and plums; also in the
seeds of apples, etc., in fact in practically all the seeds of plants of
the Rose family. It is the mother substance for "oil of bitter almonds,"
which is widely used as a flavoring extract.

Amygdalin has been the object of very extensive studies, and even yet the
exact nature of the linkage between its constituent groups is not certainly
known. When completely hydrolyzed, it yields two molecules of glucose and
one each of benzaldehyde and hydrocyanic acid. Recent studies indicate that
the two sugar molecules are separately united to the other constituents,
rather than united with each other in the disaccharide relationship. In
other words, amygdalin is a true _glucoside_ rather than a _maltoside_.
This is indicated by the fact that when submitted to the action of all
known hydrolyzing agents which affect it, it has never been found to yield
maltose as one of the products of hydrolysis. Furthermore, the rate of
hydrolysis of amygdalin is not affected by the presence of maltose; and the
segregation of the two glucose molecules is accomplished by enzymes other
than maltase, which is the only enzyme which is known to break up a maltose
molecule. Since the exact nature of the linkage is not known, it is
customary and convenient to indicate the unit groups as linked together in
the following order:

C_{6}H_{11}O_{5}-O-C_{6}H_{10}O_{4}-O-C_{6}H_{5}.CH-C[trb]N
(1) (2) (3)(4)

A study of the hydrolysis reactions of amygdalin shows that there are three
different linkages in the molecule which may be broken by the simple
interpolation of a single molecule of water and a fourth which may be split
by a different type of hydrolysis, namely, the C[trb]N linkage. These are
indicated by the numbers below the corresponding portion of the formula
above. Most hydrolyzing agents break the molecule first at (1), yielding
one molecule of glucose and one of mandelo nitrile glucoside (see page 77).
The next step usually breaks the latter at the point indicated by (2),
yielding glucose and benzaldehyde cyanhydrin, or mandelo nitrile. The
latter in turn breaks down at (3) into benzaldehyde and HCN. But when
amygdalin is boiled with concentrate