Simultaneous hemoglobin and creatinine renal clearance studies have been presented which indicate that hemoglobin is eliminated by the kidney at a rate which is 3 per cent of the creatinine clearance, above a plasma hemoglobin concentration of approximately 250 mg. per 100 cc. In dogs whose average glomerular filtration rate is 66 cc. per minute, about 2 cc. of plasma are cleared of hemoglobin per minute. A definite renal threshold exists for hemoglobin at a plasma concentration of about 100 mg. per 100 cc., below which hemoglobinuria does not occur. The uniformity of the process indicates that hemoglobinuria is not the result of a transient glomerular injury induced by the hemoglobin. It is tentatively suggested that the experimental results obtained may be interpreted in terms of the following concept. The glomerulus permits the filtration of hemoglobin in amounts directly dependent upon plasma concentration. However, only 3 per cent of all the pores of the membrane are electrostatically large enough to permit the passage of an undissociated hemoglobin molecule. Of that hemoglobin which passes down the tubule, a relatively constant though small amount is recovered by the tubules by a process not unlike that of phagocytosis found elsewhere in the body. An average value for this "athrocytic" capacity in a medium-sized dog is 2 mg. of hemoglobin per minute. This pattern of renal hemoglobin excretion is in agreement with the principles of the modern theory of kidney function.

Thiamin has a more marked accelerating effect in similar combinations, but the effect is just as evident in the cultures containing 1% oleic acid as in those containing .Ol%.With .Ol% oleic acid and 0.5% asparagin and thiamin, good growth is obtained in 5-10 days. At this time flasks without thiamin show only a trace, but after 4 weeks both show heavy and apparently equal growth. These effects were observed when as little as 1 gamma of the vitamin was added to 50 cc of medium. On the other hand, amounts of pyridoxin and thiamin up to 2.5 mg per 50 cc were without effect in the absence of oleic acid.The Pityrosporziitz ordole grows in the presence of inorganic salts, glucose and oleic acid. The addition of asparagin accelerates growth and increases the final yield.Thiamin and pyridoxin accelerate development but are not essential to the growth of this f~ingm tiiider the conditions studied. Conclusions.11928 Non-Availability of Gum Acacia as a Glycogenic Foodstuff in the Rat.

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