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                                                                     EXHIBIT 24C
 
                           SPECIAL POWER OF ATTORNEY
 
     KNOW ALL MEN BY THESE PRESENTS, that the undersigned, constitutes and
appoints JOSEPH HINES and CLARENCE J. BAUDHUIN, and each of them, his true and
lawful attorney-in-fact and agent with full power of substitution and
resubstitution, for him and in his name, place and stead, in any and all
capacities, to sign the Annual Report on Form 10-K for the fiscal year ended
July 31, 1997, for filing with the Securities and Exchange Commission by Zila,
Inc., a Delaware corporation, together with any and all amendments to such Form
10-K, and to file the same with all exhibits thereto, and all documents in
connection therewith, with the Securities and Exchange Commission, granting to
such attorneys-in-fact and agents, and each of them, full power and authority to
do and perform each and every act and thing requisite and necessary to be done
in and about the premises, as fully and to all intents and purposes as he might
or could do in person, hereby ratifying and confirming all that such
attorneys-in-fact and agents, or each of them, may lawfully do or cause to be
done by virtue hereof.
 
DATED: October 7, 1997
 
                                                  /s/  DOUGLAS AYER
 
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                                                       DOUGLAS AYER
STATE OF ARIZONA
                               ss.
County of Maricopa
 
     On this 7th day of October, 1997, before me, the undersigned Notary Public,
personally appeared DOUGLAS AYER, known to me to be the person whose name is
subscribed to the within instrument and acknowledged that he executed the same
for the purposes therein contained.
 
     IN WITNESS WHEREOF, I hereunto set my hand and official seal.
 
                                                 /s/  JANICE BACKUS
 
                                          --------------------------------------
                                                      Notary Public
 
My commission expires:
 
October 23, 1997