e or less immediate connection with the
pyridine and quinoline bases has been indicated. The conviction
accordingly forces itself upon us that, if we want to attack the problem
of building up any of these important alkaloids artificially, we must
turn to these bases as our starting point.

As already stated, both series occur in coal-tar and the pyridine series
also more abundantly in bone-oil. Pyridine, picoline, lutidine, and
collidine, the first four members of the pyridine series, have,
moreover, all been formed synthetically, although the processes are not
such as would yield the products as cheaply as they can be gotten from
Dippel's oil. Quinoline, the first member of the higher series, had been
made synthetically by several chemists, but by expensive and involved
methods, when Skraup, in 1881, effected its synthesis from nitrobenzol
and glycerin, or still better, a mixture of nitrobenzol and aniline with
glycerin. This process allows of its being made on a commercial scale if
desirable. Shortly after, by an application of the same principle,
Dobner and Miller effected the synthesis of lepidine, the second member
of the quinoline series.

At the same time that this general agreement to consider these bases as
the starting point in the endeavor to effect the synthesis of the
natural alkaloids had been arrived at by chemists, it was thought well
to look into the question whether these bases and their immediate
derivatives had any therapeutic value of their own.

Piperidine, the decomposition product of piperine, which we have shown
may be considered to be hexahydropyridine, was examined by Dr.
Kronecker, of Berlin, at the request of Prof. Hofmann, and was found to
have an action upon animals in many respects resembling that of conine.
Prof. Filehne, of Erlangen, who has studied a large number of these
pyridine and quinoline derivatives, found, moreover, that the
hydrochlorate of ethyl-piperidine had a physiological action quite
analogous to that of conine.

The physiological action of quinoline itself has been studied quite
extensively by Donath and others, and it was found that several of its
salts were quite valuable febrifuges, acting very like quinine, and
capable in cases of being used as a substitute for it. In general, the
hydrogen addition products were found to be more active than the simple
base, an observation entirely in accord with the theory formed by
Wischnegradsky, and by Konigs, as the result o