The difficulties of retaining color and shape in marine invertebrate
specimens preserved in alcohol led the Blaschkas to turn to book
illustrations as models for their early work. The illustrations
in these books were lithographed, drawn on a smooth limestone surface
and printed from the stone. This process was much faster than engraving
an image on a metal plate and thus lowered the cost of producing
an illustrated book. Lithography enabled publishers to print affordable
illustrated books, which greatly increased their popularity.