Chris,
            if its working for you why worry?
To answer some of your questions.
the clearing agent: wax mixture is to allow some of the wax in the mixture to
penetrate into the tissue. As this is carried out at room temperature it
decreases the time that the tissue needs to be in hot wax. In fact many of te
older procedures  left the tissues in the wax:clearing agent mixture overnight.
Strange as it may seem, quite a lot of the wax does actually penetrate into the
tissues during this process.
Vacuum also speeds up the infiltration of wax providing that it is not
sufficiently high to suck the paint off the laboratory wall.
If you have small, delicate larvae, I would recommend using chloroform as the
"clearing" agent because it is much more gentle than either xylene or toluene.
Chloroform does however require longer and of course it is much more toxic, also
tissue do not become tranlucent when in chlorofom. The good news is that tissue
left in chloroform for an extended period of time do not seem to become
hardened.
Barry.

"Hendry, Chris I" wrote:

> Hi all,
>
> I've been processing marine fish larvae/juvenile tissue for over a year now,
> and I've had success with my schedule so far.  However, while I was tweaking
> this schedule and whatnot, other schedules that were suggested to me
> included a vacuum during paraffin infiltration, and others suggested a
> wax/clearing agent mixture before infiltration.  Could anyone let me in on
> the importance of these modifications?  I use some of these suggestions, but
> I am simply curious about they're operation on tissue.  As well, how much
> damage would this do to my smallest, and untried, larval samples (i.e., less
> than 15 mm long, 2-3 mm thick)?
>
> Here's what I am using, FYI:
>
> 70% EtOH (indef.)
> 95% EtOH 2x1 hr
> 100% EtOH 2x1 hr
> Toluene 2x1 hr
> 50:50 Toluene:Paraffin 1 hr
> Paraplast X-tra 2 x 45 min.
> Paraplast X-tra 30 min (vacuum)
>
> Thanks for your time.
>
> > Chris Hendry
> > Graduate Student
> > University of New Brunswick/
> > Department of Fisheries and Oceans
> > Biological Station
> > St. Andrews, NB E0G 2X0 Canada
> > (506) 529-8854 Phone
> > (506) 529-5862 Fax
> > e-mail: hendryc@mar.dfo-mpo.gc.ca
> > URL: http://www.geocities.com/CapeCanaveral/Hall/9440
> >
> > To steal ideas from one person is plagiarism; to steal from many is
> > research.
> >
> >