102 Proceedings of Royal Society of Edinburgh. [sess. 
38° C. to see if any further conversion would take place. After 
being kept thus for forty-five minutes, no further change had 
occurred. The ptyalin ferment had, in this case, been killed by 
this degree of acidity of the gastric contents, viz., 0‘061 per 
cent, hydrochloric acid. 
One hour after the ingestion of the starch solution other 45 c.c. 
were syphoned off. The total acidity equalled 0T02 per cent, as 
hydrochloric acid ; much unchanged starch was present, along with 
traces of erythrodextrin and sugar. 
This also was neutralised and kept at 38° C. for forty-five minutes. 
Neither in this case did any further change occur. 
These examples illustrate that the normal acidity of the healthy 
gastric secretion not only restrains but soon kills the salivary 
ferment. 
II. Chronic Gastric Catarrh. — 250 c.c. boiled starch solution 
eaten slowly. 
1. Fifteen minutes later 45 c.c. withdrawn. 
Total acidity = 0T38 per cent, as hydrochloric acid. 
Much starch, unchanged and in soluble form, present ; also 
erythrodextrin, along with a faint trace of sugar. 
This was neutralised and kept at 38° C. for three-quarters of an 
hour, but underwent no further change. 
One hour after the starch was eaten, 38 c.c. were withdrawn. 
Total acidity = 0T96 per cent. 
A very small amount of starch was present, but no erythrodex- 
trin or sugar. 
This underwent no further change after being neutralised and 
kept at 38° C. for forty-five minutes. 
2. Same patient. 
250 c.c. starch mucilage supped. 
Ten minutes later 80 c.c. of thin white fluid were syphoned 
off. 
The total acidity reached 0T02 per cent. 
Much starch was present, unchanged and soluble, some erythro- 
dextrin, and sugar amounted to 0’4 per cent. 
