too low to dissolve the starch fibre unaided. Each of the digestive
juices has its own work to do, and the saliva acts directly upon the
starchy food; hence the importance of thoroughly masticating such food
as bread, potatoes, rice, cereals, etc. The action of heat, in baking,
which causes the vapor to rise, and forms the crust of starchy food,
produces what is called dextrine, or partially digested starch.
Dextrine is soluble in cold water, hence the ease with which crust and
toast--when properly made--are digested. It is more important to
thoroughly chew starchy food than meat, as it is mixed with another
digestive juice, which acts upon it in the stomach.


Sugars.

SUGAR.

There are many varieties of sugar in common use, viz.: cane sugar,
grape sugar or glucose, and sugar of milk (lactose). As food, sugars
have practically the same use as starch; sugar, owing to its
solubility, taxes the digestive organs very little. Over-indulgence in
sugar, however, tends to cause various disorders of assimilation and
nutrition. Sugar is also very fattening, it is a force producer, and
can be used with greater safety by those engaged in active muscular
work. Cane sugar is the clarified and crystallized juice of the sugar
cane. Nearly half the sugar used in the world comes from sugar cane,
the other half from beet roots. The latter is not quite so sweet as
the cane sugar. Sugar is also made from the sap of the maple tree, but
this is considered more of a luxury; consequently, not generally used
for cooking purposes.