The primary purpose of a bookplate is to indicate the ownership of the book in which it is located. Bookplates in books in institutional libraries often have the additional purpose of acknowledging the person or fund that purchased the book for the library. The bookplates of the St. Louis Mercantile Library (now incorporated into the University of Missouri - St. Louis Library), in addition to showing ownership, have provided a substantial amount of information about the library and its policies and procedures. I acquired several older books which had been weeded from the library and each contained a different bookplate. One of these is shown above. The bookplate indicates that the library was organized in 1846 and incorporated in 1847. It indicates that books can be kept for two weeks with a fine for detention beyond that period of two cents per day. It contains an important notice which tells the library user that damage to the book could result in a fine equal to four times its cost. Mercantile libraries were membership libraries created in the 19th century to serve merchants and their clerks. The bookplate above indicates that a clerks entrance fee was $2 with an annual subscription fee of $3. Fees for proprietors and others was $5 initially and $5 annually. A life membership could be obtained for $50. Books were evidently given an accession number and this one is number 50,371. There are some other markings which probably indicate classification and/or shelf location. The bookplate was in a novel published in 1878 titled In Paradise by Paul Heyse. Bookplates are very collectible and I have a modest collection of institutional library bookplates. You can see some my bookplates HERE. Another St. Louis Mercantile Library Bookplate article.