The appearances a t zone edges formed by the sensitive organism are shown in
P1.1, figs. 1-3, and by the resistant organism in P1.2, figs. 4-6. The thickness of
the stripped preparations makes them difficult to photograph and pen-drawings
give a better representation of observed phenomena. The only artistic liberty
consciously taken has been to represent several focal planes in the same
drawing, omitting one set of details in places in order to demonstrate others.
Micro-measuring apparatus was not available, but normal human red blood
cells were included in the high-magnification drawings to the same scale.