Abstract
1. A new peroxidase reaction is described which we believe is superior to other benzidine methods in simplicity, in sensitivity, in constancy of color and its contrast with the unstained red cells, and in the durability of the reagents used. This method is called “copper method” because of the use of copper sulphate.
2. Besides the differentiation of the myeloid and lymphoid nature of blood leucocytes the copper peroxidase reaction possesses some clinical significances, which have been related briefly.
