Although it has been established that there are definite increases in the hemoglobin and number of erythrocytes per unit of blood, loosely, designated as "blood concentration", during long exposures of human beings to low oxygen pressures (Viault, 1890 ; Dryer and Walker, '13 ; Barcroft, Harris, Orahovats and Weiss, '25) and to rapidly developed acute anoxia (Schneider and Lutz, '20), the writer has noted an apparent dilution of the blood of fishes exposed to inadequate oxygen for approximately 1 hour.
As specific gravity offers an approach to the problems of blood condition during anoxia the fluctuations in blood specific gravity in goldfish ( Carassius auratus) have been followed during controlled hppoxia. Throughout these studies the falling drop method of Barbour and Hamilton ('26) was used for the determination of blood specific gravity, and a special falling drop pipette similar to that described by Quthrie ( '32) employed.
The goldfish used in these experiments were obtained in lots of several hundred from out-of-door ponds of a commercial goldfish hatchery. I n the laboratory (pending experimental use) these fish were held in a large concrete tank through which a continuous and liberal flow of fresh, well-aerated water was maintained. The fish in the tank were fed shrimp meal every other day. It was noted in other experimental work in this SUMMARY 1. Three hundred fifty-five goldfishes (Carassius auratus) were used 2. The specific gravity of blood of fishes subjected to 1 hour of anoxic 3. The red cell count of blood from these anoxic fishes was much less 4. The specific gravity of serum from the anoxic fishes did not differ in this study. stress decreased markedly. than that of blood from control fishes. significantly from that of the control fishes.