The 55 woodblock prints of the "Memorial Edition" - published in 1891 (Meiji 24) - were printed from the original, partly reworked (added with a date and inscriptions in margin) woodblocks which first were printed by Tsuta-ya Kichizô in 1855.
“What makes any of these various later "Memorial Edition" printings recognizable from other early edition printings is the presence of the extensive "margin writing" seen in both the right and left margins of these later printings. Also typically apparent was the usage of somewhat brighter pigments which were popular in the mid-Meiji period. Amazingly, some of these "Memorial Edition" printings were PROVABLY done so still using the ORIGINAL woodblocks which were carved some 30-plus years earlier in the late 1850's. With some of these 1891 printings, we know this beyond any doubt by the distinctive "woodgrain patterns" seen in some of these prints' wider sky or water areas.“ (see Hans Olof Johannsson, E-Mail correspondence)
Strange, Edward: The Colour-Prints of Hiroshige, London 1925.
Yoneda, Shigeko / Walter, Lutz: Hiroshige: Gojûsan tsugi meisho zu-e. Edited by Gottfried Ruetz. Munich 1981.
E-Mail correspndence 2004 between Hans Olof Johannsson and Thomas Crossland about the 'Memorial Edition'.