Abstract
The author rose up into the sky as far as 4200 metres from the land, and examined the Preyer's reaction of marmots in various heights. By summarizing the results the following conclusion was reached;
I. Within the height of 4000 metres from the land, which is regarded as a safety-zone according to aeronautics the Preyer's reaction is proved positive.
II. In case of ascending flight, the decrease of the Preyer's reaction in a certain height is recovered to some extent, as soon as the examined animals become accustomed to the same atomospheric pressure.
III. Soon after the descent to a certain height, a part of the decreased reaction caused by the ascending flight is recovered; and the reaction corresponding to the atomospheric pressure appears promptly.
IV. The decrease of the Preyer's reaction does not depend upon the change of a particular pressure occasioned by a mechanical action limited to certain direction, but only upon the general change of the atomospheric pressure.
