5.6.
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143
5.5. Leitz Ultramicrotome
This instrument is a modern derivative of a microtome originally
designed by Fernandez-Moran, marketed by Leitz, Inc., Wetzler. It is a
thermal advance type utilizing a relatively short expansion arm to hold
the block. This mechanism is mounted in a small drum with appropriate
electrical connections. The entire drum is revolved to pass the specimen
across the knife edge once with each revolution. Thus, there is no backstroke or upstroke in an ordinary sense. The basic principle surely is
good, but the company has had difficulty making adequate bearings for
the revolving drum. Thus, the microtome has had a rather long history of
difficulty, although quite likely the present version has largely solved the
problem with sapphire-lined V-bearings. It remains true, however, that
the company is quite insistent that no one but factory-trained personnel
tamper with the bearing system.
The design of the microtome easily allows most of its cycle to be completed rapidly, while the small fraction concerned with the actual
sectioning is performed slowly. A somewhat complicated drive utilizing
two separate motors controls this. A long belt turns the drum on its
bearing.
I have not had experience with this microtome beyond simple demonstrations of its operation. Thus, I cannot speak authoritatively about its
use. But very high cutting speeds are possible with this instrument which
some people interested in sectioning metals find desirable, as well as do
those who have the problem of cutting rubbers and other easily deformable materials. Its minimum cutting speed is 3 mm/sec which presumably
would be used for almost all biological work. The microtome seems to
have a particularly well-designed knife holder which allows controlled
movements in all pertinent directions, including the tilt of the knife.
5.6. Reichert Ultramicrotome
This microtome is derived from a design of H. Sitte. It is made by
C. Reichert in Vienna, and is marketed in the United States through
William J. Hacker and Company, West Caldwell, New Jersey. It is a
thermal advance instrument that purports to be particularly insensitive
to local disturbances such as vibrations and air currents. The specimen
REICHERT ULTRAMICROTOME
143
5.5. Leitz Ultramicrotome
This instrument is a modern derivative of a microtome originally
designed by Fernandez-Moran, marketed by Leitz, Inc., Wetzler. It is a
thermal advance type utilizing a relatively short expansion arm to hold
the block. This mechanism is mounted in a small drum with appropriate
electrical connections. The entire drum is revolved to pass the specimen
across the knife edge once with each revolution. Thus, there is no backstroke or upstroke in an ordinary sense. The basic principle surely is
good, but the company has had difficulty making adequate bearings for
the revolving drum. Thus, the microtome has had a rather long history of
difficulty, although quite likely the present version has largely solved the
problem with sapphire-lined V-bearings. It remains true, however, that
the company is quite insistent that no one but factory-trained personnel
tamper with the bearing system.
The design of the microtome easily allows most of its cycle to be completed rapidly, while the small fraction concerned with the actual
sectioning is performed slowly. A somewhat complicated drive utilizing
two separate motors controls this. A long belt turns the drum on its
bearing.
I have not had experience with this microtome beyond simple demonstrations of its operation. Thus, I cannot speak authoritatively about its
use. But very high cutting speeds are possible with this instrument which
some people interested in sectioning metals find desirable, as well as do
those who have the problem of cutting rubbers and other easily deformable materials. Its minimum cutting speed is 3 mm/sec which presumably
would be used for almost all biological work. The microtome seems to
have a particularly well-designed knife holder which allows controlled
movements in all pertinent directions, including the tilt of the knife.
5.6. Reichert Ultramicrotome
This microtome is derived from a design of H. Sitte. It is made by
C. Reichert in Vienna, and is marketed in the United States through
William J. Hacker and Company, West Caldwell, New Jersey. It is a
thermal advance instrument that purports to be particularly insensitive
to local disturbances such as vibrations and air currents. The specimen