1. Experiments on five dogs are described consisting in the daily removal of blood plasma in amount from 25 to 100 cc. the red cells being returned to the circulation in Locke's solution. In no case was there a significant drop in plasma protein concentration.
2. A gravimetric method for the determination of total plasma protein is described.
3. A case is reported of cirrhosis of the liver in which over 10 gm. of protein daily was lost in the ascitic fluid during a period of 7 months without any lowering of plasma protein concentration.
4. The constancy of the plasma protein level and the adequacy of the mechanism of regeneration is pointed out.