was again brought up for discussion. It was thought by some that the
raphides in the different plants might vary in chemical composition,
and thus the difference in their action be accounted for. This
question the writer volunteered to answer.

Accordingly, four plants containing raphides were selected, two of
which, the _Calla cassia_ and Indian turnip, were highly acrid, and
two, the _Fuchsia_ and _Tradescantia_, or Wandering Jew, were
perfectly bland to the taste.

A portion of each plant was crushed in a mortar, water or dilute
alcohol was added, the mixture was stirred thoroughly and thrown upon
a fine sieve. By repeated washing with water and decanting a
sufficient amount of the crystals was obtained for examination. From
the calla the crystals were readily secured by this means in a
comparatively pure state. In the case of the Indian turnip the
crystals were contaminated with starch, while the crystals from the
fuschia and tradescantia were embedded in an insoluble mucilage from
which it was found impossible to separate them. The crystals were all
found to be calcium oxalate.

Having determined the identity in chemical composition of the
crystals, it was thought that there might be a difference of form of
the crystals in the various plants, from the fact that calcium oxalate
crystallizes both in the tetragonal and the monoclinic systems. A
laborious microscopic examination, however, showed that this theory
also had to be abandoned. The fuchsia and tradescantia contained
bundles of raphides of the same form and equally as fine as those of
the acrid plants. At this point in the investigation the writer was
inclined to the opinion that the acridity of the Indian turnip and