12 EXHIBIT 99.E AGREEMENT TO FILE JOINTLY We, the undersigned, hereby express our agreement that the attached Schedule 13D is filed on behalf of each of us. HOECHST MARION ROUSSEL, INC. Date: October 18, 1995 By: /s/ Rebecca R. Tilden Rebecca R....

                                                                12
                                  EXHIBIT 99.E

                           AGREEMENT TO FILE JOINTLY

     We, the undersigned, hereby express our agreement that the attached
Schedule 13D is filed on behalf of each of us.

                                        HOECHST ▇▇▇▇▇▇ ▇▇▇▇▇▇▇, INC.



Date: October 18, 1995                  By:  /s/ ▇▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇
                                             ▇▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇
                                             Vice President, Assistant
                                             General Counsel, and 
                                             Assistant Secretary


                                        HOECHST CORPORATION



Date:  October 18, 1995                 By:  /s/ ▇▇▇▇▇ ▇. ▇▇▇▇       
                                             ▇▇▇▇▇ ▇. ▇▇▇▇
                                             Secretary and Treasurer