210 Proceedings of Royal Society of Edinburgh. [sess... 
it was much less acted upon by saliva when eaten alone than when 
taken along with some indifferent fluid, as water. The greater 
moistening of the bread which results produces a marked rapidity 
in the action of ptyalin. 
Newly-baked bread is not so rapidly acted upon by saliva as 
stale bread, but the ultimate degree of starch conversion is greater 
in the former than in the latter. So far as these experiments 
show, stale bread is not more easily digested than newly-baked 
bread. 
Bread in a light and spongy condition (as is met with in well- 
aerated varieties, e.g ., Vienna bread) is more rapidly acted upon by 
saliva than when less spongy. Such bread, however, does not ulti- 
mately undergo any more complete digestion than does ordinary 
bread. 
The addition of butter to bread has little or no effect on 
amylopsis by ptyalin. Cheese, on the contrary, has a stimulating 
effect on the salivary secretion ; and, apart from the consideration of 
its digestibility, it has a helpful action in promoting starch proteo- 
lysis. 
The addition of milk to bread causes a remarkable enfeeblement 
of the salivary ferment, while broth exerts a slight restraining 
influence on it. 
When bread is chewed along with an infusion of tea, only about 
one-half the amount of sugar is formed as compared to the same 
proceeding when bread and water are alone employed. Coffee 
has no great effect in hindering or slowing starch proteolysis, and 
the same is true of cocoa. 
Beer seems to exert a stimulating action on ptyalin, as even 
from the earliest period the amount of sugar formed is in excess 
of that produced in the presence of water alone. 
Alcohol, even in dilute solution, retards salivary digestion of 
starch, but the action is much less marked than in the case 
of infusions of tea. Whisky permanently lessens the activity 
of ptyalin. 
Wines have a very marked inhibitory influence on the digestion 
of starch by saliva, and this is almost wholly due to their acidity. 
Even after three hours’ digestion in the presence of sherry, port, 
or claret starch undergoes hardly any conversion. 
