pilocarpin, with
their respective salts, the sulphate and the salicylate in the first
instance, and the hydrochlorid and the nitrate in the second, are well
established in favor and efficiency. Personally, it has always seemed to
me that the salicylate of eserin is preferable to the sulphate, but I
have not persuaded myself that the nitrate of pilocarpin possesses
material advantages over the hydrochlorid, although some authors prefer
it. With arecalin, the alkaloid of the Betel nut, I have no experience,
nor have I used its mixture with eserin, recommended by Merck as more
potent than either of the drugs in separate solution.

The substance isophysostigmin, found with eserin in Calabar bean,
according to Ogiu, exceeds in its myotic activity the sulphate of
eserin, _i. e._, 1/80 of a grain of the drug is equal to 1/60 of a grain
of the sulphate of eserin, but it is certainly not less irritating than
physostigmin, and according to Stephenson's researches, is more so, and
in this sense has no superiority over the usual alkaloid. In general
terms, it may be said that the time has not arrived to make a preachment
"on the passing of eserin and pilocarpin."

_Physiologic Action._ Concerning the ocular, physiologic action of the
two chief alkaloids respectively of Calabar Bean and of Jaborandi, there
still exists difference of opinion. It has always been easy to attribute
the myotic action of these drugs, or at least, of eserin, to their
stimulant action on the peripheral ends of the oculo-motor, thus causing
sphincter contraction, and to a depressing action on the sympathetic
fibers, thus causing removal of the action of the dilatator of the iris.
But complete experimental proof of such action is wanting, and it is
probable that myosis follows a direct stimulation of the sphincter
muscle fibers, aided, perhaps, by contraction of the iris vessels,
although the last named effect is denied by so competent an authority as
Hobart Hare.

Exactly how the myotics reduce intra-ocular tension is not definitely
proven. Usually it is taught that because of the myosis the base of the
iris wedged in the angle of the anterior chamber is loosened and
withdrawn, precisely as a fold in a coat is straightened by a tug on the
fabric beneath it. Experiments, however, for example, by E. E.
Henderson, have shown that the rate of filtration in an eye with
artificially raised pressure is considerably larger when it is under the
influence of eserin