Thank you to all who responded with sources for celloidin - I have passed 
them along to the investigator who wanted the info.
Andi
.....................................................................
: Andrea Grantham, HT(ASCP)     Dept. of Cell Biology & Anatomy     :
: Sr. Research Specialist       University of Arizona               :
: (office:  AHSC 4212)          P.O. Box 245044                     :
: (voice:  520-626-4415)        Tucson, AZ  85724-5044    USA       :
: (FAX:  520-626-2097)          (email:  algranth@u.arizona.edu)       :
:...................................................................:
           http://www.cba.arizona.edu/histology-lab.html