2. When N-isoleucine is added to a fed supplement of methionine or methionine and cystine, the utilization of parenterally given hemoglobin N is even better than with the sulfur-containing amino acids alone.

3. A suggested approach to the problem of designing the quantitatively "ideal" amino acid mixture lies in the definition of what may be called total organism-amino acid patterns of rat, dog, man, etc. These may vary considerably not only at different developmental stages in a given species, but also certainly from one species to another.

4. Further attempts to detect globin in the peripheral circulation have pointed to the need for a highly specific procedure such as that an immunologic method may offer.

5. Reduced hemin in dog plasma migrates with ₁-globulin and albumin in veronal buffer at pH 8.5 and the colored zones give strong hemochromogen absorption bands.