Given healthy dogs, fed abundant iron and protein-free or low protein diets, with sustained anemia and hypoproteinemia due to bleeding, we can study the capacity of these animals to produce simultaneousiy new hemoglobin and plasma protein.

The reserve stores of blood protein-producing materials in this way are largely depleted, and levels of 6 to 8 gm. per cent for hemoglobin and 4 to 5 gm. per cent for plasma protein can be maintained for considerable periods of time. These dogs are very susceptible to infection and to injury by many poisons. Dogs tire of these diets and loss of appetite terminates many experiments. These incomplete experiments are not recorded in the present paper but give supporting evidence in harmony with those tabulated.

Under these conditions (double depletion) the dogs use effectively the proteins listed above—egg, lactalbumin, meat, beef plasma, and digests of various food proteins and hemoglobin.

Egg protein at times seems to favor slightly the production of plasma protein when compared with the average response (Tables 1 and 2).

Various digests and concentrates compare favorably with good food proteins in the production of new hemoglobin and plasma protein in these doubly depleted dogs.

Whole beef plasma by mouth is well utilized and the production of new hemoglobin is, if anything, above the average—certainly plasma protein production is not especially favored. "Modified" beef plasma by vein causes fatal anaphylaxis (Table 4).

Hemoglobin digests are well used by mouth to form both hemoglobin and plasma protein. Supplementation by amino acids is recorded. Methionine in one experiment may have been responsible for a better protein output and digest utilization (Table 7).

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