32 Proceedings of Puoyal Society of Edinburgh. [sess. 
solution I had previously employed, that I made a 6 -6 p.c. solution 
of cane sugar and added to it 0'05 p.c. hydrochloric acid. I kept it 
at the temperature of the body for two hours, and found that it con- 
tained 0“66 p.c. of invert sugar. 
The amount of invert sugar formed in this case being only 0’66 
p.c., compared with 0*83 p.c. when diluted gastric juice was used, 
seems to bear out Leube’s statement that sugar inversion is less rapid 
and less energetic with a pure solution of hydrochloric acid than 
with gastric juice. 
It has been definitely stated in some text-books that there is a 
sugar-inverting ferment in the gastric secretion. I therefore sought 
to determine whether the inversive action of the acid is aided by 
such a ferment. I mixed equal volumes of healthy gastric fluid, 
water, and 20 p.c. solution of cane sugar, and then carefully 
neutralised the acidity with potassium hydrate. After keeping this 
mixture at the usual temperature for an hour there was no trace of 
invert sugar ; after two hours a faint trace of sugar had appeared, but 
too minute for quantitative estimation. 
Therefore, when the acidity of gastric juice is neutralised, no 
inversion of cane sugar occurs. I therefore conclude that there is 
practically no sugar-inverting ferment in gastric juice, otherwise an 
appreciable amount of invert sugar would have been formed in the 
experiment I have detailed. 
My experiments have therefore convinced me that the acidity of 
the gastric juice is the only factor in producing inversion of sugar in 
the stomach. 
I now sought to determine what changes cane sugar undergoes 
when introduced into the stomach. I experimented on a healthy 
man by the following method : — At 8 a.m. he had breakfast of 
porridge and milk. Two hours afterwards I washed out his stomach 
with a syphon tube, and then poured 250 c.c. of a warm 20 p.c. 
solution of pure cane sugar into the stomach. At intervals of from 
half an hour to two hours after the injection I passed the stomach- 
tube and removed some of the gastric contents. Each sample of the 
gastric fluid so obtained was measured and filtered, and the reduc- 
ing sugar in it estimated by Fehling’s solution. The total acidity 
was estimated with a centinormal solution of caustic soda, and 
expressed in terms of anhydrous hydrochloric acid. 
