1. IN AN ISOLATOR STRUCTURE HAVING AN ENCLOSURE INCLUDING A PORT DEFINING MEMBER, A CLOSURE MEMBER SEALABLE TO SAID PORT MEMBER, SAID CLOSURE MEMBER INCLUDING A SEVERABLE MEMBRANE, ANOTHER ENCLOSURE POSITIONABLE ADJACENT THE FIRST MENTIONED ENCLOSURE AND HAVING AN OPENING, MEANS INCLUDING A SECOND SEVERABLE MEMBRANE CLOSING SAID OPENING, MEANS FOR SECURING SAID MEMBRANES IN ADJACENT OPPOSING RELATIONSHIP AND FOR PROVIDING AN ANNULAR SEAL AROUND A SPACE BETWEEN SAID MEMBRANES, AND SAID MEMBRANES BEING SEVERABLE FOR PERMITTING ACCESS BETWEEN SAID ENCLOSURES WHILE MAINTAINING SAID ENCLOSURES SEALED FROM THE SURROUNDING ATMOSPHERE.