14 



FOOD INGESTION AND ENERGY TRANSFORMATIONS. 



after the main meal of the day, independent of the hour at which it is 

 taken. Scharling did not overlook the importance of noting the pulse 

 rate, both in the fasting experiments and in those preceding and fol- 

 lowing the ingestion of food. Although his results may now have 

 but little quantitative value, it is of importance to note that Scharling 

 was the first to employ successfully the chamber principle of studying 

 the respiratory exchange. 



Vierordt, 1845. The next two contributions to the experimental 

 research on the respiratory exchange as affected by the ingestion of 

 food unfortunately deal with a very imperfect method for both samp- 

 ling and analyzing the expired air. Vierordt, 1 in making a very large 

 number of observations on himself, employed a mouthpiece con- 

 sisting of a short tube over which the lips closed. The nostrils were not 

 closed during the experiment, as Vierordt thought it was impossible to 

 breathe simultaneously through nose and mouth during quiet, normal 

 respiration. The expired air was collected in a glass vessel containing 

 9,200 c.c., which was filled with a solution of common salt. About 

 1| minutes were required to fill this vessel completely with expired air. 

 Vierordt based his carbon-dioxide measurements on 1-minute periods, 

 making two experiments in an hour. A mixed diet was taken in the 

 food experiments. Of special interest in this connection are the 

 comparisons made by Vierordt between the food experiments and the 

 fasting experiments. On two occasions when he had not eaten since 

 7 a. m., he obtained values while still fasting at 2 p. m. He compares 

 the average of these two fasting experiments with the average of his 

 experiments made at 2 p. m. just after eating. This comparison is 

 shown in table 1. 



TABLE 1. Comparison of results obtained during fast and afterfood (Vierordt). 



(Values per minute.) 



From other experiments made when meals were taken at different 

 times of the day, he concludes that the digestion of the evening meal 

 proceeds with less energy than that of the noon meal. His conclusion 

 is in part borne out by the fact that the pulse after the evening meal 

 did not show the marked rise which was found after the noon meal. 



Wierordt, Physiologic des Athmens, 1845. 



