At a recent meeting of Ohio State Microscopical Society this subject 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 calla was due to the presence of an acrid principle.

Since the works on pharmacy claimed that the active principle of the Indian turnip was soluble in ether, the investigation was continued in this direction.  A large stem of the calla was cut into slices, and the juice expressed by means of a tincture press.  The expressed juice was limpid and filled with raphides.  A portion of the juice was placed into a cylinder and violently shaken with an equal volume of ether.  When the ether had separated a drop was placed upon the tongue.  As soon as the effects of the ether had passed away, the same painful acridity was experienced as is produced when the plant itself is tasted.  This experiment seemed to corroborate the assumption of an acrid principle soluble in ether.  The supernatant ether, however, was slightly turbid in appearance, a fact which was at first ignored.  Wishing to learn the cause of this turbidity, a drop of the ether was allowed to evaporate on a glass slide.  Under the microscope the slide was found to be covered with a mass of raphides.  A portion of the ether was run through a Munktell filter.  The filtered ether was clear, entirely free from raphides, and had also lost every trace of its acridity.