What about the idea that these type of cards were used by the "Traveling Salesmen" picking up sample beads from the cultures they were doing business with and having an ample supply of these card stock blanks, making field notes for future research into the types of beads that are popular with said culture, in order to make beads that would be comparable substitutes? Gathering cards with local beads and making notations would seem like an easy way of conducting the market research of the time, it sure beats bringing home a sack or strands of beads for later analysis! Just my thought, Thomas
PS thanks for the posts