14 VITALITY AND EFFICIENCY WITH RESTRICTED DIET. 



representing scarcely half the dog's requu-ements. While Pettenkofer 

 and Voit have not specifically discussed in detail the undernutritional 

 stage of this series of experiments, their data are referred to and in a 

 certain sense recalculated by Rubner.^ In discussing these and some 

 other experiments Rubner recognizes that, in addition to the loss in 

 body substance produced by acute or prolonged hunger, the heat-pro- 

 duction usually decreases in proportion to the decrease in mass, but 

 points out the possibility of individuality. In Pettenkofer and Voit's 

 experiments, while there was no measurable loss in carbon-dioxide 

 excretion per kilogram of body-weight during the period of under- 

 nutrition, in which the body-weight varied from 34.4 to 30.0 kg., there 

 was a much greater heat-production, as measured by the carbon-dioxide 

 output, with a diet of 1,500 grams of meat than with 1,000 grams. 

 The fact that the actual basal metabolism was not measured makes it 

 difficult to interpret these experiments as evidence of a decrease in the 

 basal metabolism due to undernutrition. 



Klemperer, 1889. — Although based primarily upon nitrogen meas- 

 urements and body-weight rather than upon the metabolism, Klem- 

 perer 's^ conception of the adjustment of the body to high or low diets 

 is the first clearly formulated. In his celebrated experiment on a 

 tailoress, Klemperer, arguing from the fact that body nitrogen was in 

 equilibrium and that consequently the calories must have been in 

 equilibrium, maintained that this individual could, when resting in 

 bed, subsist upon 18 calories per kilogram per 24 hours. Both experi- 

 ment and conclusion have been adversely criticized by von Noorden,^ 

 but Klemperer was the first to indicate ''die Moglichkeit und Wahr- 

 scheinlichkeit verringerten Energieumsatzes" or "die Lehre von der 

 Anpassung des Umsatzes an die gereichte Kost.'"* 



Lehmann, Mueller, Munk, Senator, and Zuntz, 1893. — The classic 

 experiments made by Lehmann, Mueller, Munk, Senator, and Zuntz^ 

 on two fasting men must be interpreted in the light of the present day 

 knowledge of the influence of fasting upon metabolism. Zuntz and 

 Lehmann concluded, because the heat production of the subject 

 Breithaupt after the fast was less, even with a larger diet, than before 

 the fast (24.8 as compared with 27.3 calories per kilogram per 24 hours), 

 that with certain conditions the undernourished body may use food- 

 stuffs more economically than a well-nourished body, but emphasize 

 the fact that further information is desirable. We now know that 

 fasting per se depresses the metabolism. The ingestion of food first 

 offsets this depression, then stimulates the metabolism to higher 



^ Rubner, Gesetze des Energieverbrauchs bei der Ernahrung, Leipsic, 1902, pp. 296-297. 

 2 Klemperer, Zeitschr. f. klin. Med., 1889, 16, p. 597. 



' von Noorden, Metabolism and practical medicine, 2, Pathology, Chicago, 1907, foot-note 

 1, p. 5. 



* Magnus-Levy, Zeitschr. f. klin. Med., 1906, 60, p. 203. 



* Lehmann, Mueller, Munk, Senator, and Zuntz, Arch. f. path. Anat. u. Physiol., 1893, 131, 



Supphft., p. 1. 



