JURISDICTION OF THE COURT - ARBITRATION CLAUSE - CONTRACTUAL RELATIONSHIP BASED ON SUCCESSIVE CONTRACTS - REPLACEMENT OF AN ORAL CONTRACT BY ANNUAL WRITTEN CONTRACTS - ABSENCE OF ANY ARBITRATION CLAUSE IN THE FIRST WRITTEN CONTRACTS - ARBITRATION CLAUSE INCLUDED IN EACH OF THE CONTRACTS SIGNED SUBSEQUENTLY - CONSIDERATION BY THE COURT OF ALL THE CONTRACTS SUCCESSIVELY ENTERED INTO ( ECSC TREATY , ART . 42 ; EEC TREATY , ART . 181 ; EAEC TREATY , ART . 153 )