CALCIUM OXALATE IN THE DASHEEN 
449 
Samples of dasheen, both tubers and leaves, were placed at the 
writer's disposal through the kindness of Mr. R. A. Young, of the 
Office of Foreign Seed and Plant Introduction, and they were used in 
the work which follows in an endeavor to settle the point as to whether 
the raphide content was the sole factor in causing the acridity of this 
plant. 
The family of the Araceae to which the dasheen belongs is known to 
produce in several instances alkaloids, glucosides, and bitter substances, 
any of which if present in the plant under investigation might be wholly 
or partially responsible for its peculiar flavor. Samples of dasheen 
leaves were, therefore, distilled with steam on the assumption that 
they might contain a volatile compound, possibly an alkaloid. The 
distillate, however, failed to show the presence of any body of this 
nature. Further experiments were made on the dried leaves, which 
were exhaustively extracted with various solvents, namely, petroleum 
ether, ethyl ether, chloroform, acetic ether, alcohol, and water in 
rotation. These extracts, likewise, after evaporating the solvent, 
showed no evidence of an acrid flavor, but the observation was made 
that the residual leaf matter was no longer unpleasant to the taste, 
although when examined under the microscope the raphide cells were 
still intact and apparently in perfect condition. At first sight this 
seemed to be proof that the raphides had no connection with the acrid 
taste of the leaves, but on further investigation it was found that when 
cells from these extracted leaves were brought into contact with water 
they had wholly lost their capacity to expel the individual needle 
crystals, a fact which might very well acount for their loss of virulence. 
The facts brought out in this series of experiments, namely, that the 
various extracts and the residue v/ere all without acrid effect, seem to 
force us back on the raphide theory of acridity, with the additional 
proviso that free movement of the raphides is necessary to secure the 
effect. It might, nevertheless, be contended that acridity is destroyed 
in the process of extraction by the decomposition of some compound, 
though the possibility seems remote. 
To secure more direct evidence of the mechanical effect of raphides 
on the mouth an attempt was made, with a moderate degree of success, 
to synthesize calcium oxalate in fine needle forms as near as could be in 
size and shape to naturally-occurring raphides. It was found that 
when a dilute solution of calcium chloride was slowly dropped into a 
dilute solution of oxalic acid, crystals of calcium oxalate separated. 
