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.

The same operations were repeated upon the Indian turnip with exactly
similar results.

These experiments show conclusively that the acridity of the Indian
turnip and calla is due to the raphides of calcium oxalate only.

The question of the absence of acridity in the other two plants still
remained to be settled. For this purpose some recent twigs and leaves
of the fuchsia were subjected to pressure in a tincture press. The