The second postwar series of definitives was issued on 20 October 1950. For the first time in nearly fifty years the responsibility for a complete definitive series was entrusted to a single designer. The series has consequently visual unity and its impact was increased by the simultaneous issue of all values. The artist chosen was the doyen of Italian stamp designers, Corrado Mezzana, whose first series had been the 1930 Virgilian commemoratives. He died in 1952. The 1950 definitives are therefore among his last work; they are also among his best. The theme of the series is 'Italy at work' (Italia al lavoro). The first postwar definitives had been dedicated to the principles of liberty and democracy; in three of the designs was the implication that the attainment of these principles depended upon work and skill. The 1950 series took work and skill as its sole theme and associated it with the special contribution of different regions. Each stamp showed a worker exercising a skill particularly associated with one region or another against a background which usually included a glimpse of a famous monument or view within the region. The subject matter of these stamps has been treated in some detail, not only because the information cannot quickly be obtained from English-language reference books but also to emphasize the exceptional skill with which the elements of design have been assembled in this series. The lower values were printed gravine with the usual perforation ; the 100L. and 200L. were printed recess. These two values show the slight variations in line perforation typical of Italian recess stamps of this period. Of the 100L, it is possible for the specialist interested in quarter perforations to assemble about seventeen different perforations, the extremes being 14 1/4 and 13 1/4. In rare cases, during 1952, one of the lateral perforations measured 11 1/4. This variety is not known unused. The perforations of the 200L. do not vary so extensively, but this stamp also is known with a lateral perforation of 11 1/4. The 100L. was engraved by Vittorio Nicastro and the 200L. by Trento Cionini. From 1950 the collector interested in the watermarks has to distinguish between three types of winged wheel and at least two types of stars watermark. Since these watermarks appear on a number of stamps they are discussed in a special section to which reference should be made. The first issue of the 'Italy at work' series had the winged wheel type I except for the 100L. and 200L., which had type II. Between February 1952 and February 1955 all values below 100L. except the 6L. and 55L. were reissued with the winged wheel type III. Between March 1955 and April 1957 seven values (50C, 1L., 2L., 15L., 30L., 65L.) were issued with the type I stars watermark and the 15L. also (March 1956) with type II stars. These stamps are found overprinted saggio (diagonally on the 5L., 6L., 20L., 100L., 200L.). The series ceased to be valid after 31 March 1958.