tol blue and "virtual plants"

Wilson Taylor taylorwa at UWEC.EDU
Wed Oct 8 12:36:48 EST 1997


Hi Ross and everyone,

>I have used the simple aqueous Tol blue solution and my students
>get fairly good results...but NEVER beating phloroglucinol/HCl.
>
>The secret to Phloroglucinol is making the phloroglucinol
>in an alcoholic solution. 

Ok. This is new to me.

>I use HCl in a separate dropper
>bottle diluted 1 conc HCl to 4 parts water (resulting in about
>10% HCl final conc).  Apply the two drops to a specimen and
>in about 10 seconds the results are spectacular.  For long-term
>storage and classroom use, I prefer Nalgene dropper bottles
>with unitary caps.  You never get more than one drop at a time
>and nothing degrades in the acid.

Er, you add two drops of what?  One of HCl and one of phloroglucinol?  What
is the concentration of PGL?  In what conc. of ethanol I presume.  I'd like
to try this as at least a demo.

>What I don't like about Phloroglucinol is the corrosion you can
>get on mechanical stages and the tips of objective lenses if
>the students aren't meticulous with the acid...and promptly
>removing the slides from the stages before storing the microscopes.

This is exactly why I stopped using it.  Tol blue (aq) does give equivocal
results with lightly lignified cells (e.g., some protoxylem), but with some
specimens, it, too, is excellent.  Just this year I stumbled upon Cleome
("spider plant").  We sometimes section unknowns in my plant anatomy class,
and it was great with tol blue - it looked like a prepared slide.  The main
problems I encounter with hand sectioning in my intro botany are the
thickness and obliqueness of the sections - they can't evaluate the quality
and I can't check every one.  They do, however, seem to enjoy making their
own slides.  I used to think that students had trouble making the connection
between prepared slides and live plants.  I came to abandon that doubt a few
years back (thinking "of course they know these are real plants, what else
could they believe?") - until this year.  A student actually asked me a few
weeks ago if these slides were "real."  I suspect I'm wrestling with the
first generation to have their concepts of "real" shaken by virtual techology.

Wil Taylor
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Wilson A. Taylor
Department of Biology
University of Wisconsin-Eau Claire
Eau Claire, WI  54701
taylorwa at uwec.edu

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