Texas Journal of Microscopy - Texas Society for Microscopy

during the class break between lecture and lab. We generally
talked about students because then, as today, they are always
of interest to instructors. However, on the day in question, we
discussed the use of electron microscopy in the study of plant
cells. Specifically, we spoke about a recent paper by Dr. Flora
Murray Scott, a distinguished plant anatomist at UCLA, and her
colleagues. Her paper presented electron micrographs of onion
epidermal cells (Scott, et al., 956). However, we could not relate
her micrographs to plant cells as seen in the light microscope.
In fact, “we” dubbed her micrographs “rug patterns.” We had
a great laugh about these “useless pictures!” (I think that “Rug
patterns” was probably Foster’s idiom, in fact sometimes I used
“Wallpaper patterns” when relating this incident). Obviously,
we did not have much regard for the use of electron microscopy
in the study of plant cells. That “contempt” especially on my part,
is incredible, when you realize that in just few years, I was fully
engaged in studying plant cells with the electron microscope. By
the early 960’s Dr. Scott published electron micrographs that
contained obvious plant cells components. Her 956 paper was
apparently near the beginning of her use of electron microscopy
to study plant cells. Foster stuck with the tried and true and never
moved on to electron microscopy.
Figure 4. “Mollenhauer Cover” appeared on TSEMJ 22(2),
1991. The cover was created by H .J. Arnott by adapting a
micrograph from Whaley, et al.; 1960.
In 960 I was back in Berkeley teaching Botany in summer
school. That summer, Foster and I discussed a recent paper by
W. Gordon Whaley, H. H. Mollenhauer and J. H. Leech, “The
ultrastructure of the meristematic cell” (Whaley, et al., 960). It
got our attention “big time.” In fact, “That paper changed everything!”
Here was electron microscopy that showed real plant
22 Tex. J. Micros. 38: , 2007
cells, not “rug patterns.” Now we could actually see plant cells in
transmission electron micrograph, images that corresponded to
what we could see in the light microscope. However, there was
a critical difference, now we could see the internal details of
plant cells that microscopists struggled to make out since the time
of Leeuwenhoek and Hooke. There were “the granules,” that E.
B. Wilson spoke of in his book on cells (Wilson, 928). Unknown
to us, in the previous year, Hilton H. Mollenhauer reported on
the KMnO4 fixation of plant cells (Mollenhauer, 959). That paper
was the real breakthrough and it gives Mollenhauer (alone)
the priority for the introduction of permanganate fixation of plant
cells. Dr. Hilton H. Mollenhauer was president of the Texas Society
of Microscopy in 985-86 and was honored by a festschrift
given by the Society in 996 and a cover showing one of Mollenhauer’s
classic micrographs of permanganate fixed plant cells
(Fig. 4).
Now, let’s go back to the crystal trail. In 963-64 Jack Horner,
a graduate student of mine at that time (see Part III), and I began
to study transmission electron microscopy in the lab of Professor
James C. Hampton, Chair of the Department of Anatomy, Northwestern
University Medical and Dental Schools, Chicago, Illinois.
We received excellent direct instruction from both Hampton and
Benjamin (Ben) Rosario. However, preparation of thin sections
was difficult, as glass knives didn’t work well with plant material.
In any event, at that time I began looking for a plant system to
study and my thoughts brought back the raphide crystal cells of
yucca. Like Quatermain remembering the map. I promptly fixed
some yucca root tips using KMnO4 and embedded them in Epon.
Later, I purchased a diamond knife and sectioning became much
easier. In 964, at the American Botanical Society meeting in
Denver, I gave a paper entitled “The Ultrastructure of the Yucca
Root” in which I spoke about the electron microscopy of raphide
idioblasts for the first time (Arnott, 964). It is interesting to note
that Dr. George R. Johnstone was in the audience at my presentation.
That was the last time I saw my USC mentor; he died in 97 .
I spoke of my “stroke of luck” in being accepted in the Graduate
School at Berkeley (see Part III). By another similar “stroke of
luck” I arrived at The Cell Research Institute, UT Austin, late in
964. I became an NIH postdoc with Gordon Whaley and began a
critical training program in electron microscopy. I transferred my
NSF grant on “The Anatomy of Yucca,” to the University of Texas
and soon graduate students (not mine) were in the field (in Mexico
and South Texas) collecting and fixing yucca material. The
students somehow got the “idea” that it would be good to freeze
the fixed specimens – of course, nothing could have been worse.
All their collecting was for naught, since the freezing destroyed
the integrity of the specimens and made them useless to me.
That “setback” ended a research avenue that I hoped to follow,
namely, to study the anatomy and ultrastructure of yucca.
However, I was already examining the ultrastructure of several
kinds of plant idioblastic CaOx crystal cells, and with the fixation
setback, they became my chief area of study (plan B). In retrospect,
“the crystal trail” was an outstanding choice, even if it was
forced by circumstances. Some of my first crystal cell samples,
in addition to Yucca, were duckweed, Lemna minor, the water
hyacinth, Eichhornia crassipes and the castor bean, Ricinus communis
(Plate 3). They were all fixed with KMnO4.
In each of these species the formation of CaOx crystals, i.e.,
“crystal production system,” was different in specific ways; however,
they had many common characteristics. All produced the
CaOx crystals in the vacuole, a truly significant point since the
plant vacuole at that time was characterized as a simple water
sac. Even though I suggested that the crystals of yucca appeared
to be in the vacuole (Arnott, 962), electron microscopy made it
“crystal clear.” In Eichhornia I found over 2000 needle-shaped