But it is not altogether advisable to take this short cut to relief, because the salivary juice contains what the drink of water does not--a _ferment_, or digestive substance (_ptyalin_), which possesses the power of turning the _starch_ in our food into _sugar_.

As starch is only very slowly soluble, or "meltable," in water, while sugar is very readily so, the saliva is of great assistance in the process of melting, known as _digestion_.

The changing of the starch to sugar is the reason why bread or cracker, after it has been well chewed, begins to taste sweetish.
This change in the mouth, however, is not of such great importance as we at one time thought, because even with careful mastication, a certain amount of starch will be swallowed unchanged.

Nature has provided for this by causing another gland farther down the canal, just beyond the stomach, called the _pancreas_, to pour into the food tube a juice which is far stronger in sugar-making power than the saliva, and this will readily deal with any starch which may have escaped this change in the mouth.

Moreover, this "sugaring" of starch goes on in the stomach for twenty to forty minutes after the food has been swallowed.
Starchy foods, like bread, biscuit, crackers, cake, and pastry, are really the only ones which require such thorough and elaborate chewing as we sometimes hear urged.