The Rate of Metabolism of Some Small Mammals

The experiments upon which this report is based were designed primarily to determine the oxygen consumption and consequently the rate of metabolism of several species of small mammals. Since oxygen consumption is an accurate measure of the energy utilized by an animal and reflects the food consumption and activity, it can be useful in understanding the habits and requirements of different species in the wild. Most existing measurements of oxygen consumption have been made under rather strict "basal" conditions, and runs of as long as 24 hours covering the complete daily cycle of a nocturnal or diurnal animal have seldom been made. Furthermore, other authors, with few exceptions, have studied laboratory or domesticated animals, and it is felt that the weight of these observations should be balanced by more observations on wild animals. Doubtless in most instances the laboratory animals submit more gracefully than their wild relatives to the investigations of the physiologist, but it is possible that the characteristics which fit them for domesticity also separate them as a group from the wild animals. Selection of lethargic individuals for laboratory breeding may have increased any metabolic difference that existed originally. Indeed, the white mouse, which many laboratory zoologists consider to be extremely nervous and restless, appears quite lazy when compared to some of the animals treated in this report, especially the shrews.