Influence of Ingestion of Food. 517 



The third method, namely, study of the course of the recovery after fasting, 

 obviously requires a longer time than the 2 or 3 days' sojourn in the respiration 

 calorimeter after a fasting period. It is necessary, therefore, to resort to 

 studies of metabolism which can be made outside of the respiration chamber, 

 namely, those of the intake and output of nitrogen, sulphur, phosphorus, etc., 

 and such studies as have been made with S. A. B., in connection with these 

 experiments receive special discussion beyond. 



Unfortunately, the effect of the ingestion of food immediately after the 

 fast could not be studied in these experiments under conditions which even 

 approximated the ideal conditions outlined above. In connection with the 

 fasting experiments here reported four experiments in which food was ingested 

 were made, during which the subjects remained inside the respiration chamber 

 continuously from 1 to 3 days. It was soon seen that a practical difficulty was 

 experienced that had not been anticipated, namely, that it was difficult, if not 

 indeed dangerous, to administer a large amount of food on the first day fol- 

 lowing a fast. Consequently, the quantity of food administered had to be very 

 much restricted and the effect on metabolism and digestibility was correspond- 

 ingly diminished. Usually not until the second day after the fast could any 

 considerable amount of food be taken. Thus the important observations on 

 the first day were made under great disadvantages. 



Furthermore, the separation of feces was in every case extremely difficult. 

 While no difficulty was experienced in the separation at the end of the food 

 period, the sharp separation of the feces properly apportioned to the food 

 period from the mass of fecal matter that had been retained in the colon 

 during the whole of the fast was extremely difficult. The feces that had been 

 for a long time in the alimentary tract had been deprived of their water, so 

 that, at least in one instance, the water content was as low as 50 per cent. 

 This mass became more or less mixed with the softer, fresher feces as they were 

 forced through the colon and it was separated after expulsion only with diffi- 

 culty. Under these circumstances, then, the results obtained during the 3-day 

 calorimeter experiments in studying the problem of the effect of the ingestion 

 of food after fasting from the standpoint of the influence on digestibility and 

 on the total metabolism have a value considerably less than it was hoped they 

 would have. 



It was, furthermore, apparent that this method of studying the effect of the 

 ingestion of food after fasting was impracticable, and that an entirely different 

 type of experiment must be used for a proper study of this problem. Accord- 

 ingly, during the past year experiments have been in progress in this laboratory 

 in which large quantities of food were ingested after a short fast (12 to 18 

 hours) rather than after a period of inanition covering several days. 



The method of studying the effect of the ingestion of food after a short fast 

 was suggested by the data secured in the fasting experiments here reported. 



