98 General Aspects of Fasting [Sept 



The blood of fasting subjects which are ingesting water shows 

 in general a decrease in the number of erythrocytes and leucocytes, 

 and of the percentage of hemoglobin. The differential distribution 

 of leucocytes varies with the species. In the dog (12) there is a 

 decrease in the percentage of polymorphonuclear leucocytes and a 

 corresponding increase in the small lymphocytes. The changes in 

 the other forms of cells are but nominal. 



Fasting studies have been of great importance in the study of 

 the minimum of food necessary to maintain life and upon which 

 to base the calculation of dietary Standards. Such studies have also 

 been utilized in the explanation of phenomena occurring in patho- 

 logical States and of metabolism in general. 



Underhill and Rand (25) have explained certain anomalies in 

 the urinary changes which occur in pernicious vomiting of preg- 

 nancy from their knowledge of fasting metabolism. 



Two agriculturalists have recently made use of the results of 

 fasting studies to elucidate problems of importance to both the 

 scientist and the farmer. McCollum (16), fed a nitrogen-free diet 

 to pigs and studied the efficiency of individual grains as feeding 

 stuffs, as well as the nature of the repair processes in protein metab- 

 olism. He shows that the difference in the nutritive values of the 

 wheat, oat and corn kerneis is not so great as would be expected 

 from the difference in the chemical composition; and further, that 

 the repair processes of the cell are of a different character from 

 those of growth, and that the cellular catabolism and repair do not 

 involve the destruction and resynthesis of entire protein molecules. 

 This last Statement is not in entire accord with the most widely 

 accepted theories of metabolism. Certain zoölogists have also 

 shown that the changes of regeneration are unlike those which occur 

 in growth. 



Dietrich^ shows (7) that fasting so reduces the plane of metab- 

 olism that the quantity of food which was insufficient for main- 

 tenance before fasting was afterward sufficient, not only for main- 

 tenance, but to produce a positive nitrogen balance ; in other words, 

 the animals were more efficient machines after fasting. 



'I wish to thank Professor Dietrich of the University of Illinois for per- 

 mission to refer to his unpublished data. 



