The influence of labyrinthine stimulation by accelerated rotation on the hemogram was observed in the dogs by means of Prof. Hasegawa's accelerating rotation apparatus, and the effect of sodium bicarbonate solution was also observed.The results were as follows:1) In the normal dogs, after subjected to uontinuous stimulation for 15, 30 and 60 minutes, no change in the blood cell count was noted, but the chang in the differentiol leucocyte count was noted; relative lymphocytosis was noted temporarily, neutrophils were rather decreased, and there was no change in eosinophil and monocyte count.2) Bilaterally labyrinthectomized dogs showed almost no change in hemogram, irrespective to the length of the stimulation..3) Normal dogs previoosly trea.el with 2cc/kg of 7% sodium bicarbonate solution also remained unaffected, notwithstanding continuous subjection to the rotatory acceleration.4) In this experiment, the change in differential leiucocyle count, as the result of the accelerating stmuli, was interpreted as a phenomenon of sympatheticotonic reaction through the labyrinth.It was especially pointed out that this effect of the labyrinthine stimulation could be prevented by the injection of sodium bicarbonate.