[LETTERHEAD]





                                                                    Exhibit 23.3




                           CONSENT OF DARBY & DARBY P.C.


      We hereby consent to being named under the heading "Experts" in the 
Prospectus constituting part of this Registration statement on Form S-1 with 
respect to information contained under the captions "Risk Factors--Uncertainty 
of Patents and Proprietary Rights" and "Business--Patents and Proprietary 
Technology."



/s/ Peter Ludwig
- -------------------------
Darby & Darby, P.C.


New York, New York


November 19, 1997