1 66 



PHYSIOLOGICAL CHEMISTRY 



Calculation. Note the number of cubic centimeters of N/ioo NaOH required 

 to neutralize i c.c. of stomach contents, and multiply it by 10 to obtain the number 

 of cubic centimeters N/io NaOH necessary to neutralize 100 c.c. of stomach 

 contents. This is the method of calculation most widely used. For other forms 

 of expressing total acidity see page 177. Plot your results in a form similar to 

 those shown in Figs. 51 and 52. 



Curves Obtained by the Fractional Method. When an Ewald test meal 

 is given to normal individuals a curve such as indicated below is usu- 

 ally obtained. The curve may vary within certain limits depending on 

 individual idiosyncrasies, but is usually found to follow the curve 

 depicted, and the meal normally leaves the stomach in two and one- 



100 



60 



60 



40 



20 



total ac 

 free ac. 1 



20 40 60 80 100 120 minutes 



FIG. 51. ACIDITY CURVES OF NORMAL HUMAN STOMACH. 



half hours. Pathologically every variation occurs, both in time of 

 evacuation as well as the character of the curve and the quantity of the 

 secretion elaborated. Fig. 45 represents some of the possibilities of 

 pathological cases, but a consideration of their interpretation is outside 

 the purpose of the present volume. It will be evident, however, from 

 a consideration of the figure that the cycle of gastric digestion is a con- 

 stantly changing one, and no information concerning the trend of 

 digestion can be obtained by an examination of only a single stage of 

 digestion. Marked changes may precede or follow that stage and the 

 possibilities suggested in Fig. 45 are all observed clinically and are of 

 varying significance. Typical curves from cases of hyperacidity, 

 gastric carcinoma and achylia are shown in Figs. 52, 53 and 54 

 respectively. 



