Biology Reference
In-Depth Information
FIGURE 2.7
Karl von Nageli (1817
e
1891).
Using thin leaves of the common aquarium plant Elodea, the location of the plasma
membrane can be more readily observed than by light refraction. The outer plasma
membrane barrier defines a track around which tiny green chloroplasts are carried by cyto-
plasmic streaming. This can be very easily detected by simple light microscopy.
In his day von Nageli was a highly respected botanist. Among his discoveries were chro-
mosomes and the function of many plant parts including antheridia and spermatozoids of
PLASMOLYSIS
H
2
O
H
2
O
turgid
plasmolyzed
high
low
osmotic strength
FIGURE 2.8
Plasmolysis in a plant cell. At a critical osmotic strength of the media, water leaves the cell and the
plasma membrane pulls away from the cell wall. At this point the cell is said to be 'plasmolyzed'.
