I just learned that Polish emigrants passing through the Russo-German boarder on their way to Hamburg had to pass through control stations at Bajohren, Tilsit, Eydtkuhnen, Insterburg, Prostken, Illowo, Otloczyn, or Ostrowo where they were medically examined and admitted for transport. These stations were controlled by the Hamburg-America and North German Lloyd, but overseen by the Prussian government. Then, they were moved through Ruhleben, and checked again, before being allowed to Hamburg for departure. Has anyone located any records from these control stations? Do they exist?