In Japan, hypoplastic anemia has ever been presenting one of the most important problems among today's anemic diseases, it having proved as great frequency as that of pernicious anemia found both in Europe and America; besides, no fit therapeutic method been discovered as yet. Generally speaking, this disease shows a decrease of entire corpuscles, the bleeding tendency becoming prevalent in most cases; yet as to signs in concern to bone marrow, the number of nuclear cell is not fixed, as it has proved 16, 200 at the lowset, while, 263, 000 at the highest. Consequently, it has been classified into 5 types in our department, in view to obstructions of bone marrow. 1. Type of bloodcell-arrest. 2. Type of maturation-arrest. 3. Type of disturban...