Observations on certain physiological processes of the marmot.II.—The respiration

Many observers, of whom the earliest appear to have been Valentin (1870), Dubois (1896), Patrizi (1897) and Pembrey and Pitts (1894), have made graphic records of the respiratory movements in marmots. These were all registered by stethographic and similar methods. Such do not give quantitative data of the depth of respiration and of the total ventilation. The depth, the rate, and incidentally the total ventilation have now been studied simultaneously by an apparatus described by one of us (Endres, 1930). These records were taken either when the marmot was asleep in cold air with which it was in equilibrium, or when it had just been removed from such an atmosphere to a warmer one. In the latter case, the temperature of the marmot rose and ultimately the animal awoke. It is known that, when the marmot is awaking, its rectal temperature frequently differs from that of its mouth or its heart (see previous paper); and that when the marmot is asleep the disparity is less. Nothing, so far as we know, is known about the temperature of the marmot’s brain (respiratory centre) as compared with other parts of the body. It cannot be claimed that even during sleep the rectal temperature is more than an approximation, to within a few degrees, of the body temperature. The general features shown by the respiratory records observed when a marmot was asleep during hibernation are as follows. Taking Experiment 7 as an example, the rectal temperature of the marmot was 1° C. at the beginning of the experiment. Though the marmot was asleep its respiratory activity at this temperature was relatively high: in this connection it must be remembered that sufficient cold wakes the marmot. It has been suggested to us by Pembrey that, on the border of awakening, the contact between the nose and the mask may have stimulated respiration.