EXPLANATION OF PLATES 
All figures were made by aid of ;'; Leitz oil-immersion lens and a drawing 
camera at an original magnification of 2000 diameters, which was reduced one- 
third in reproduction. Figures 1 to 32 are from smear preparations of blood, 
stained with Wright’s stain; figures 33 to 73 are of sections of the red marrow of 
the femur, fixed in a corrosive-sublimate-formalin solution and stained according 
to Wright’s technic for demonstrating the origin of blood-platelets from mega- 
karyocytes. 
