By observing the influences of temperature on the motility of pseudoesinophils in bone-marrow tissue culture of rabbits (cover-slip method) the author obtained the following results: 1. The limit of temperature that enables such observations lies in the range between 15℃, the minimum and 43℃, the maximum. 2. The maximum wandering velocity is found at 39℃, whereas the peak of the wandering velocity appears faster at a higher temperature and slower at a lower temperature. 3. As for the movement pattern, at the temperature showing the peak of wandering velocity, pseudoeosinophils of Types A and B appear most numerously; and also many pseudoeosinophils of Type F can be seen at a higher temperature. 4. At a certain stage in the limit temperature of both the maximum and minimum (43℃, 15℃) there appear a similar specific type, namely, the cell presenting a dumbbell-like shape having pseudopodia connected with the cell body at their veryr narrow part. 5. As for the shapes of pseudopodia, those presenting tongue-shape or saw-like ones tend to be most numerous at any temperature, and those with bleb shape or flag shape tend to be more numerous at a higher temperature. Those possessing no pseudopodia appear more at a lower temperature. 6. Relatively numerous tail-threads appear in an early stage at temperature of 37℃, 39℃, or 41℃, but generally these do not appear at a lower temperature, with one exceptionally peculiar thing is that only in an early stage at the low temperature of 15℃ cells with many tail-threads make their appearance. 7. Either at the temperature lower than 30℃ or higher than 39℃, and with the lapse of time the ratio of the long axis against the short axis grows smaller.