32 MISSOURI BOTANICAL GARDEN. 
the cell by the contracting protoplasm. When this happens 
the bands generally lose their spiral form and appear as 
irregular masses of green. 
Thus, when the cells are plasmolysed by a strong solution, 
the chlorophyll bands are not displaced and lie, after plas- 
molysis, entirely outside of the protoplasm. If, on the other 
hand, a weaker solution is used and plasmolysis is brought 
about more slowly, the chlorophyll bands are carried toward 
the center of the cell and lie, after plasmolysis, entirely within 
the protoplasmic mass. When the cells plasmolysed by a 
strong solution are observed under a low-power microscope, 
they do not appear to be plasmolysed. The chlorophyll 
bands still occupy their normal position, and the spherical 
protoplasmic masses being quite hyaline are difficult to dis- 
tinguish. 
When the cells are plasmolysed by a strong solution, the 
membrane surrounding the protoplasm must be broken in 
many places in order to allow the escape of the chlorophyll 
bands. Ifthe membrane is differentiated from the remainder 
of the protoplasm, 7. ¢., if there is really a membrane sur- 
rounding the protoplast, one would expect it to lose its semi- 
permeability after such treatment. Certainly no inert mem- 
brane with which we are acquainted could be used to 
demonstrate osmosis after being broken in so many places. 
The spherical masses of protoplasm that have been freed of 
their spiral bands will, nevertheless, take up water and 
enlarge if the solution in which they are immersed be 
diluted with distilled water. No success has accompanied 
efforts to make the spherical masses enlarge sufficiently to 
fill the entire cell. They always burst and disintegrate 
before they have enlarged to that extent. These proto- 
plasmic masses take up water, although any membrane 
which may have surrounded the cell in its normal condi- 
tion must have been broken when the chlorophyll bands 
passed out through the surface layers of the protoplasm. 
This experiment was often repeated, and always with the 
same results. 
If a membrane surrounds these Spirogyra cells in their 
