GAISER: CRYSTALS IN THE SPADIX OF ANTHURIUM 393 
As noted, Wakker considered the proof adequate that the 
origin of crystals is in the vacuole. Kohl (8), on the other hand, 
held to their origin in the mass of the colloidal cytoplasm itself. 
In classifying calcium oxalate crystals in respect to the positions 
they occupy in the plant cell he recognized three types. They 
may: (I) appear as inclusions in the protoplast; (2) be lodged 
in the membrane; or, finally, (3) be attached to the cell wall. 
If crystals may appear in the cell membrane and are surrounded 
by a cellulose sheath, Kohl considered it probable that they 
originate in the cell plasma, since only by its activity could the 
crystal be encapsuled by a cellulose sheath. 
Pfeffer (15, p. 95) considered the possibility of a passage of 
crystals through the plasma. In the plasmodia of Myxomycetes 
he claims amoeboid movements serve mechanically in taking 
into the substance of the protoplasm foreign particles. These 
are carried to the interior and, penetrating the vacuoles, are 
expelled from time to time. Crystals like other solid bodies 
might be so transferred and in protoplasts bounded by a cell 
wall would collect in the cell sap. 
The proof that crystals, either clearly visible in the vacuole 
or less evidently so, are surrounded by a plasma sheath is pro- 
bably inadequate. The older observation of Payen (14) of 
aggregates of crystals so enclosed in the cells of Cacti needs 
confirmation. In general, acids have been used to first dissolve 
the salt and leave the crystal sheath. Such methods of deter- 
mination involve the risk of inaccuracy, since the possibility 
that the so-called sheath is a precipitation or shrinkage product 
is not sufficiently considered. Osterhout (12) has shown that 
shrinkage may be caused by other means than the use of hyper- 
tonic solutions. 
Deviations from the general occurrence of plasmolysis in a 
cell when placed in a solution whose osmotic pressure exceeded 
that of the cell sap led him to suspect that a contraction of the 
protoplasm might be due to the chemical action of a salt. This 
conception wasconfirmed by finding that plasmolysis of Vaucherta 
zoospores in a 0.0001 m. solution of NaCl was prevented when 
a little CaCl, was added. By putting in the minute amount of 
one molecule for every hundred molecules of NaCl the proto- 
plasm of the algal cells showed no contraction even though the 
solutions reached one thousand times greater osmotic pressure 
