EXHIBIT 3.20

                          CERTIFICATE OF INCORPORATION

                                       OF

                               MEDIC SYSTEMS, INC.

         FIRST:   The name of the corporation is Medic Systems, Inc.

         SECOND:  The address of the corporation's registered office in the
State of Delaware is Corporation Trust Center, 1209 Orange Street, in the City
of Wilmington, County of New Castle. The name of the corporation's registered
agent at such address is The Corporation Trust Company.

         THIRD:   The purpose of the corporation is to engage in any lawful act
or activity for which corporations may be organized under the Delaware General
Corporation Law.

         FOURTH:  The total number of shares of stock which the corporation is
authorized to issue is one thousand (1,000) shares of common stock, having a par
value of one dollar ($1.00) per share.

         FIFTH:   The business and affairs of the corporation shall be managed
by or under the direction of the board of directors, and the directors need not
be elected by ballot unless required by the by-laws of the corporation.

         SIXTH:   In furtherance and not in limitation of the powers conferred
by the laws of the State of Delaware, the board of directors is expressly
authorized to make, amend and repeal the by-laws.

         SEVENTH: A director of the corporation shall not be personally liable
to the corporation or its stockholders for monetary damages for breach of
fiduciary duty as a director, except for liability (i) for any breach of the
director's duty of loyalty to the corporation or its stockholders, (ii) for acts
or omissions not in good faith or which involve intentional misconduct or a
knowing violation of law, (iii) under section 174 of the Delaware General
Corporation Law, or (iv) for any transaction from which the director derived an
improper personal benefit. If the Delaware General corporation Law is amended to
authorize corporate action further eliminating or limiting the personal
liability of directors, then the liability of a director of the corporation
shall be eliminated or limited to the fullest extent permitted by the Delaware
General Corporation Law, as so amended. Any repeal or modification of this
provision shall not adversely affect any right or protection of a director of
the corporation existing at the time of such repeal or modification.

         EIGHTH:  The corporation reserves the right to amend and repeal any
provision contained in this Certificate of Incorporation in the manner from time
to time prescribed by the laws of the State of Delaware. All rights herein
conferred are granted subject to this reservation.

         NINTH:   The incorporator is Karen A. Gimbutas, whose mailing address
is P.O. Box 1347, Wilmington, Delaware 19899.



                                                                    EXHIBIT 3.20


         I, THE UNDERSIGNED, being the incorporator, for the purpose of forming
a corporation under the laws of the State of Delaware do make, file and record
this Certificate of Incorporation, and, accordingly, have hereto set my band
this 14th day of September, 1995.

                                                 /s/ KAREN A. GIMBUTAS
                                                 ---------------------
                                                     Karen A. Gimbutas