. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology. 1!)(i() MAMMALIAN 111BKRNATI0N 323 pressures the ground squirrels always cooled faster than did the rats. The curves tended to level off at a lower body temperature as the exposure progressed. The ground squirrels at '_'()() nun He; and 150 nun Hg cooled at approximately the same rate, although there is a marked difference in oxygen deficiency. The ground squirrels at 150 mm Hg and at a chamber temperature of '_!:!(' cooled almost as fast as those at 14 C. If the cooling- constant 4 b 40 35 -- 30 25 — 20 15 sxm TEMP.
. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology. 1!)(i() MAMMALIAN 111BKRNATI0N 323 pressures the ground squirrels always cooled faster than did the rats. The curves tended to level off at a lower body temperature as the exposure progressed. The ground squirrels at '_'()() nun He; and 150 nun Hg cooled at approximately the same rate, although there is a marked difference in oxygen deficiency. The ground squirrels at 150 mm Hg and at a chamber temperature of '_!:!(' cooled almost as fast as those at 14 C. If the cooling- constant 4 b 40 35 -- 30 25 — 20 15 sxm TEMP. h. CONTROL PERIOD —? «—ALTITUDE EXPOSURE PERIOD RECOVERY, PERIOD 20 40 0 TIME —\- 20 I N 40 M I N 60 U T E S 80 100 120 Fig. 2. The changes in body temperature of one squirrel taken to a 150 mm Hg barometric pressure at a chamber temperature of 14°C. is estimated from Newton's law of cooling, which takes into accounl the difference between body temperature and ambient temperature, the constant is higher in the squirrel at 23°C. This may be indicative that the cooling process is of a regulated nature and that the squirrel can utilize a maximum cooling procedure if necessary. In another series of experiments, the living ground squirrels in the first 30 minutes of exposure to 150 mm Eg cooled faster than dead rats, and at approximately the same rate as dead ground squirrels. Localized temperature changes upon hypoxic exposure. Figure 1> shows the curves for various body temperatures ob tained for one ground squirrel. Typically, the colonic and. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Harvard University. Museum of Comparative Zoology. Cambridge, Mass. : The Museum
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