One hundred years ago the smile you were born with or grew soon there after, was pretty much as good as it got.  In fact, you could probably count on things getting worse as you got older and at best you could expect false teeth if you could afford them in cash.
These days we [...]

Machinery of Digestion.-From the number and differently formed structures which constitute the digestive organs, it will be observed that the function is a very highly complex process.  If the food were thrown directly into the circulating fluid, it could not be used for the purpose of nutrition.  It requires for its transformation into blood, bone [...]