Abstract: Disclosed herein is a culture bag which has a culture room formed by fusion-bonding a transparent sheet and at least one opening formed therein, the sheet being made of a resin composition composed of 100 parts by weight of vinyl chloride homopolymer or copolymer and 150-260 parts by weight of ethylene-n-butyl acrylate-carbon monoxide copolymer, and having a gas permeability of 600-3000 ml/m.sup.2.24hr.atm to oxygen and a gas permeability of 1000-30,000 ml/m.sup.2.24hr.atm to carbon dioxide.

Abstract: A method of connecting plastic tubes by high-frequency heating comprising preparing an electrode block having at least two electrode members each having annular bores aligned with each other, the electrode block including at least one insulator interposed between the electrode members, the insulator having a bore aligned with those of the electrode members, inserting an end portion of one tube into the one electrode member and an end portion of the other tube into another electrode member so that both tube ends keep contact with each other in the bore of the insulator, and applying a high frequency voltage between the electrode members.