found in ergot, and hordein,
found in barley, are examples. The former has marked medicinal properties.
There is no known physiological use for these simple amines in plants. By some investigators, they are regarded as intermediate products in the synthesis or decomposition of proteins; but it would seem that if this were a normal procedure, these amines would occur in varying proportions in all plants, under different conditions of metabolism, instead of in practically constant proportions in only a few species, as they do.
ALKALOIDS
These are a group of strong vegetable bases whose nitrogen atom is a part of a closed-ring arrangement.
As a rule, alkaloids are colorless, crystalline solids, although a few are liquids at ordinary temperatures. They are generally insoluble in water, but easily soluble in organic solvents. Being strong bases, they readily form salts with acids, and these salts are usually readily soluble in water.
Alkaloids are usually odorless; although nicotine, coniine, and a few others, have strong, characteristic odors. Most of them have a bitter taste, and many of them have marked physiological effects upon animal organisms, so that they are extensively used as narcotics, stimulants, or for other medicinal purposes.
Most of the alkaloids contain asymmetric carbon atoms and are, therefore, optically active, usually levorotatory, although a few are dextrorotatory.