extensions for short legs, crutches, braces, abdominal supporters, and various other applications to supplement the defects of the body have been devised. _Digestion._--The physiology of digestion had, perhaps, the first real light shed upon it by Beaumont’s observations from 1825 to 1832. A Canadian boatman, Alexis San Martin, was wounded in the abdomen from a charge of buckshot, and the wound healed, leaving a permanent opening in the stomach, through which the operation of digestion could be observed. This furnished visible evidence of the relative digestibility of different kinds of foods, and the general functions of the stomach. The peculiar and different conditions governing the digestion of the starch foods, the albumenoids (such as meat and fish), and the sugars and fats, have been clearly ascertained, and “what is one man’s food is another man’s poison” is now susceptible of intelligent diagnosis and effective adjustment. Of late years the stomach has been greatly aided in its functions by prepared or predigested foods. The action of diastase, in converting starch into grape sugar, has been taken advantage of, and cereals treated with diatase, malted milk, lactated and peptonized foods, have proven a boon to the enfeebled digestion, while the intelligent study of dietetics has done much to relieve the physician and promote the health of the individual by right living. _Bacteriology._--Although Leeuwenhoeck discovered the bacterium in 1668-1675, up to 100 years ago disease and death were largely regarded as dispensations of Providence, and with fatuous resignation were accepted as inevitable. The microscope and the study of bacteriology, however, have revealed to us the presence of minute living organisms or germs, which are everywhere around us, infesting the air, the earth, the water, our food, our bodies, and all organic matter in countless millions. These infinitely small beings multiply with a rapidity and fecundity that bewilders the imagination. Their method of multiplication is by fissiparism--that is to say, each splits into two independent beings that separate and afterwards lead independent lives. It is said that there is one species in which not more than six or seven minutes are required for the division to take place. A single individual might consequently produce more than a thousand offspring in an hour, more than a million in two hours, and in three hours more than the number of inhabitants on the globe. They are known as micro-organisms, of which the bacteria are the most important. The bacteria are further divided into species, and names are given them to distinguish the different forms. The little rod-shaped ones are called _bacilli_: the spheroidal ones _micrococci_ or _cocci_. If they cling together in chains they are called _streptococci_; if of a spiral or corkscrew form they are called _spirallae_. The curved bacilli are called “_comma_” _bacilli_, from their resemblance to the punctuation mark of that name.