Abstract
Observations have been made in various diseases on the effect of vitamin B_<12>upon the migration velocity of neutrophils which was used as a criterion for the defense mech anism of living organisms. (1)Generally speaking, vitamin B_<12> accelerates the migration velocity of neutrophils which was lowered in diseases associated with macrocytic anemia. (2)In some cases of hapatic diseases or others vitamin B_<12> has a similar effects, but not necessarily depending upon the types of accompanying anemia.
