The elements of the science of nutrition / by Graham Lusk.

  • Graham Lusk
Date:
1917
Catalogue details

Licence: In copyright

Credit: The elements of the science of nutrition / by Graham Lusk. Source: Wellcome Collection.

    149/850 (page 149)
    It is evident from the table that there was a constant decrease in the metabolism as the air was warmed from o° to 3 50 C. The metabo- lism at o° was two and a half times that at 30°, an increase as pro- nounced as is incurred as the result of severe muscular work. The animal at o° was not observed to move around any more than he did at 30°. These results have been confirmed by Murschhauser.1 Other experiments confirmed Rubner in the view that the critical temperature, or the temperature of the minimum metabolism, lay at 330. At this point temperature had the least influence on total metabolism. When the temperature is raised from 30° there is at first no increase in the metabolism. This is due to the action of the apparatus for the physical regulation of body temperature. As the temperature rises the blood-vessels of the skin become dilated and the evaporation of water from the body is promoted. These factors tend to maintain the normal temperature of the organism by physical means. If the temperature of the air be high, so that the physical regulation be not sufficient to cool the body, then a supernormal temperature ensues. Such a febrile temperature raises the metabo- lism by warming the cells, as is seen in the table of the experiment in which the guinea-pig was exposed to a temperature of 40°. Almost identical with the experiment given above and subject to the same analytical interpretation is that of Goto,2 who exposed a rat to different environmental temperatures and measured its heat production with the following results: Temperature of Air °C. Calories per Sq. M. ist Day of Fast 2D Day of Fast 5 1942 1848 13 1628 1571 20 1186 1089 25 976 834 28 845 789 30 896 908 33 1062 982 In the rat Goto finds that the lowest level of basal metabolism is usually at 28° C. 1 Murschhauser, H.: Z. physiol. Chem., 1912, 79, 301. 2 Goto, K.: Biochem. Z., 1923, 135, 107.