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 XXXXXX XXXXXXX, INC.



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


                                        HOECHST CORPORATION



Date:  October 18, 1995                 By:  /s/ Xxxxx X. Xxxx       
                                             Xxxxx X. Xxxx
                                             Secretary and Treasurer