The encapsulation of exudates, excretions, extravasations, disintegrating tissues, germs, parasites, bullets and other foreign bodies renders them harmless. The processes and structures it evolves are plainly defensive measures. They once more remind us of the many and varied emergency measures the body has at its command.

A process similar to this is seen in plants that have been invaded by parasites. The large, rough excrescences seen on oak trees form about the larva of a certain fly. This fly lays its eggs beneath the bark of the tree. The larva which develop from the eggs secrete a substance that results in the formation of the huge timorous mass. Large tumor-like masses form on the roots and stalks of cabbage as a result of parasitic invasion. The olive tree also develops tumors from a similar cause; while, cedar trees present peculiar growths, called "witches' brooms," as a result of a fungus growing on them. There are many other examples and they are all quite obviously protective measures. Tumor formation is undoubtedly due to a variation in the complex relations determining normal growth and is of a distinctly protective nature. A tumor is not a source of danger until it begins to break down.

Of a similar nature to cyst formation is the forming of stones, as in the lungs in tuberculosis. When calcification of an area of the lungs occurs the tubercular degeneration ends in that area. I have seen a piece of metal similarly encapsulated with stone, in the lungs.

An unusual piece of engineering which shows, in a remarkable manner, the ingenuity of nature in her efforts at prolonging life in spite of every obstacle, is recorded by J. F. Baldwin, A.M., M.D., F.A.C.S., in a surgical paper dealing with transfusions. He performed an operation on a middle aged woman who had been having frequent hemorrhages from her bowels for several years. He says: "At the operation I removed a snarl of small bowel, making the usual anastamosis. Examination of this snarl showed that there had been an intestinal obstruction, but Nature had overcome it by ulceration between adherent loops of the bowel above and below the obstruction. The ulcer persisted, however, and it was its persistent bleeding that caused her anemia. She made an excellent recovery and got fat and hearty."

It looks like a real intelligence at work when nature causes two folds of the bowels to adhere together and then ulcerates through them in order to make a passage around the obstruction. There can not be the slightest doubt that the ulcer would have healed, leaving a passage, and the bleeding stopped, had the opportunity been afforded it. Nature probably cried out day after day in unmistakable language for the cessation of feeding long enough for her to complete her engineering feat. But this was never given her. The ulcerated surface was kept constantly irritated with food, and drugs as well.

An aneurism is an inflated portion of an artery. If the walls of an artery become weak at a given place, they either burst, or some of its coats are strengthened, or else it becomes bulged out due to the pressure of the blood from within. The body at once sets about to protect itself by forming a wall of new tissue around the aneurism. Should it rupture so that the blood finds its way along between other organs, a wall of scar tissue is thrown up around the aneurism to limit the escape of blood. This is called a dissecting aneurism.

A thrombus is a small blood-clot formed inside of a blood vessel. The condition is called thrombosis and the vessel is said to be thrombosed. They are the result of injury and inflammation and may completely plug the vessel.

In the intestines are many small glands composed of lymphoid structure just as are the tonsils of the throat, and known as Pyer's patches. In typhoid fever these patches are swollen or enlarged (hypertrophied) and frequently they suppurate. They may slough off. This peeling off may result in a hemorrhage or it may not depending on whether or not all the vessels in that locality are tightly thrombosed. If they are all tightly thrombosed no hemorrhage occurs. If the work of sealing the vessel is not complete or perfect then a hemorrhage occurs with more or less loss of blood before it finally ceases. This is but another evidence of nature's engineering work. These thrombi may later be swept into the general circulation and carried to some vital spot where they are too large to pass through the artery and may there cut off the blood to parts of the organ causing it to die of starvation. Starvation would only occur in cases of stopping of an "end-artery." "Anastamosing" arteries would soon establish sufficient collateral or compensatory circulation to supply the part with blood.

In every disease we observe the living organism altering its function to meet existing conditions. The reactive symptoms of disease may be broadly divided into two general classes--namely, those represented by reduced or suspended function, and those represented by accelerated function. As these will be dealt with more in detail in another chapter we will do no more than mention them here. Suspended or reduced function is intended to conserve power while accelerated function is intended to actively meet and overcome the foes of life. The study of these phenomena is one of the most interesting studies in the whole realm of biology, although, at present, its surface has only been scratched.

As a means of adjustment and adaptation which enables the body to prolong its life Nature always favors the most vital organs. This is as it should be. Life would not last long under many conditions, if nature treated all organs alike and caused each organ to suffer equally under those conditions. If the heart or brain, for instance, were not given preference over the hair or nails, if the hair and nails were treated as though they were of equal importance as the heart and lungs, man would perish in many conditions through which he now passes with a minimum amount of harm.

The more important organs are securely packed away in places of greatest safety, and every possible safeguard thrown around them. The brain is carefully wrapped in two delicate membraneous covers between which is a serous fluid which serves as a shock absorber and all this is encased in a hard bony safe which protects from all ordinary influences.

The gray matter of the spinal cord after being carefully wrapped in membraneous sheaths and protected by the spinal fluid is also encased in a flexible column of bone and cartilage. Its branches, the spinal nerves, are carefully cushioned in a fine mesh-work of connective tissue, the meshes of which are filled with a semi-fluid, compressible fat. The spinal column is so constructed that it combines great strength with a maximum of flexibility and the articulations are such that no luxations or sub-luxations are possible without such violence that there is a tearing of ligaments and cartilage and a breaking of the articulating processes of the vertebrae. No vertebra can touch the spinal nerves. To serve as a further shock absorber, preventing jarring of the brain from running or walking, the spinal column is normally curved in three places so that it acts much as the springs on an automobile.