Viscosity of protoplasm in plant cell and animal cell
Answers
Answered by
0
William Seifriz
Introduction
The first descriptions of protoplasm, written nearly a century
ago, characterize it as "a living jelly." While protoplasm is
often of high viscosity, any restricted statement is likely to be
misleading, for the viscosity of protoplasm may vary from a con-
sistency slightly more than that of water to that of a firm jelly.
From descriptions to be found in current literature it is rather
difficult to know of just what degree of viscosity the living sub-
stance might be. The difficulty lies in the fact that there has
been no careful systematic attempt to ascertain the exact degree
of consistency of protoplasm from numerous types of cells and
under many different physiological conditions. The following
paper represents such an attempt.
Method
The method used has been that of microdissection. The instru-
ment employed in this method is a modification of the Barber
pipette holder (i). It consists essentially of two needle holders,
each capable of three movements. The holders are fastened to
the microscope stage, and the two needles held in them project
into a glass moist chamber in which the material to be worked
upon is suspended in a hanging drop of water on the under side of
a cover slip which forms the roof of the chamber. The needles
are of glass and possess exceedingly fine but rigid tips. The
technique of the microdissection method is fully described by
Chambers (7), to whose article the reader is referred.
The harmful consequences which are likely to result from the
practice of holding material in a thin water film, and the importance
of this to microdissectionists, make it advisable to direct attention
1 Botanical Contribution from the Johns Hopkins University, no. 66.
Botanical Gazette, vol. 70] [360
i 9 2o] SEIFRIZ— PROTOPLASM 361
to the frequently damaging effect of this method by presenting
some experimental data.
In working with material in a hanging drop it is often very
desirable to have the water film of such thinness that the material
is held firmly against the cover slip. The surface tension between
water and glass thus produced is quite sufficient to hold an active
protozoan such as Euplotes in a fixed position, or to flatten out
marine ova, making them more transparent and dissection easier.
If the material thus subjected to surface tension suffers no appreci-
able distortion, no harmful consequences may result, but eggs of
seaweeds and echinoderms are sufficiently pliable to be readily
distorted, so that the protoplasm is subjected to an abnormal
strain which frequently causes rapid deterioration.
In order to ascertain in a general way the harm done through
the flattening of marine ova by a water film, I made a series of
observations on the ova of the sea-urchin Tripneustes. These
eggs were placed in a large and much spread water droplet, which
was of greater depth at its center than the diameter of an egg,
while toward the periphery the water film gradually thinned to
an imperceptible depth. Ova in the center of the droplet were of
a normal spherical shape, while those in the peripheral film were
much flattened. In half an hour the viscosity of the protoplasm
of those eggs in deep water had risen only slightly, while the
viscosity of those in the peripheral film had greatly increased. In
an hour the spherical ova had risen in viscosity a barely perceptible
amount, while the flattened ones had become a firm gel. Further-
more, the distorted eggs tolerated less dissection before showing
pronounced disorganization, retained the capacity for healing a
wound for a shorter time, and, in a great number of cases, their
entire contents dispersed suddenly at the first touch of a needle.
While the use of the surface tension of a thin water film is of
value in holding material for microdissection, therefore, the method
must be used cautiously. Indeed, the greatest care possible must
be taken to keep the material living and normal, and to become
familiar with those criteria which assist in ascertaining the exact
condition of the living substance. A full appreciation of the
extreme irritability of protoplasm is a prerequisite to successful
Introduction
The first descriptions of protoplasm, written nearly a century
ago, characterize it as "a living jelly." While protoplasm is
often of high viscosity, any restricted statement is likely to be
misleading, for the viscosity of protoplasm may vary from a con-
sistency slightly more than that of water to that of a firm jelly.
From descriptions to be found in current literature it is rather
difficult to know of just what degree of viscosity the living sub-
stance might be. The difficulty lies in the fact that there has
been no careful systematic attempt to ascertain the exact degree
of consistency of protoplasm from numerous types of cells and
under many different physiological conditions. The following
paper represents such an attempt.
Method
The method used has been that of microdissection. The instru-
ment employed in this method is a modification of the Barber
pipette holder (i). It consists essentially of two needle holders,
each capable of three movements. The holders are fastened to
the microscope stage, and the two needles held in them project
into a glass moist chamber in which the material to be worked
upon is suspended in a hanging drop of water on the under side of
a cover slip which forms the roof of the chamber. The needles
are of glass and possess exceedingly fine but rigid tips. The
technique of the microdissection method is fully described by
Chambers (7), to whose article the reader is referred.
The harmful consequences which are likely to result from the
practice of holding material in a thin water film, and the importance
of this to microdissectionists, make it advisable to direct attention
1 Botanical Contribution from the Johns Hopkins University, no. 66.
Botanical Gazette, vol. 70] [360
i 9 2o] SEIFRIZ— PROTOPLASM 361
to the frequently damaging effect of this method by presenting
some experimental data.
In working with material in a hanging drop it is often very
desirable to have the water film of such thinness that the material
is held firmly against the cover slip. The surface tension between
water and glass thus produced is quite sufficient to hold an active
protozoan such as Euplotes in a fixed position, or to flatten out
marine ova, making them more transparent and dissection easier.
If the material thus subjected to surface tension suffers no appreci-
able distortion, no harmful consequences may result, but eggs of
seaweeds and echinoderms are sufficiently pliable to be readily
distorted, so that the protoplasm is subjected to an abnormal
strain which frequently causes rapid deterioration.
In order to ascertain in a general way the harm done through
the flattening of marine ova by a water film, I made a series of
observations on the ova of the sea-urchin Tripneustes. These
eggs were placed in a large and much spread water droplet, which
was of greater depth at its center than the diameter of an egg,
while toward the periphery the water film gradually thinned to
an imperceptible depth. Ova in the center of the droplet were of
a normal spherical shape, while those in the peripheral film were
much flattened. In half an hour the viscosity of the protoplasm
of those eggs in deep water had risen only slightly, while the
viscosity of those in the peripheral film had greatly increased. In
an hour the spherical ova had risen in viscosity a barely perceptible
amount, while the flattened ones had become a firm gel. Further-
more, the distorted eggs tolerated less dissection before showing
pronounced disorganization, retained the capacity for healing a
wound for a shorter time, and, in a great number of cases, their
entire contents dispersed suddenly at the first touch of a needle.
While the use of the surface tension of a thin water film is of
value in holding material for microdissection, therefore, the method
must be used cautiously. Indeed, the greatest care possible must
be taken to keep the material living and normal, and to become
familiar with those criteria which assist in ascertaining the exact
condition of the living substance. A full appreciation of the
extreme irritability of protoplasm is a prerequisite to successful
Answered by
0
Protoplasmic viscosity in Plant and Animal Cells
A living jelly is how protoplasm is described in the earliest writings, which date back nearly a century. Even while protoplasm frequently has a high viscosity, any generalized statement about it is likely to be false because its viscosity can range from slightly higher than that of water to that of a solid jelly.
Animal cells are often smaller than plant cells. 8. Compared to plant cells, the cytoplasm of animal cells is denser and more granular.
- There is less vacuole in animal cell cytoplasm compared to plant cytoplasm. And the cyclosis movement is also responsible for this in plant cell.
- There are more ions in animal cytoplasm. So to perform chemical reaction and enzyme work it should be more denser.
- Having more organelles and absence of cell wall animal cytoplasm is more thick.
- Throughout evolution the species are getting advanced adaptability and change them continuously. As the plant body structure is simpler than animal so it is obvious that animal cytoplasm is much denser,.
#SPJ2
Similar questions