1. In vitro blood studies using the artificial kidney are discussed in detail.
2. In vitro experiments in which samples of blood in cellophane tubing are rotated on the drum showed a diminution in the red cell volume, leukocyte and platelet counts.
Dilution, caused by the passage of the dialyzing fluid through the cellophane membrane and by the presence of some of the rinsing fluid, and rotation of the drum are factors of importance in this regard.
3. The influence of heparin and the chemotactic role of cellophane on the leukocytes are discussed.
Heparin in concentration of 1 mg./10 cc. of blood causes in vitro agglutination and disintegration of leukocytes after approximately one hour.
Photographs are shown that demonstrate coating of the cellophane by granulocytes. This is in keeping with the findings of Chambers and Grand that cellophane exerts a positive chemotactic influence on the granulocytes.
4. Hypersegmentation of the leukocytes was noted in samples of blood rotated on the drum for fifteen minutes. Exteriorization and slow speed centrifugation probably account for this phenomenon.